NEW Validate DBFields

NEW Allow database read-only replicas

_config/model.yml

@@ -20,6 +20,8 @@ SilverStripe\Core\Injector\Injector:
     class: SilverStripe\ORM\FieldType\DBDecimal
   Double:
     class: SilverStripe\ORM\FieldType\DBDouble
+  Email:
+    class: SilverStripe\ORM\FieldType\DBEmail
   Enum:
     class: SilverStripe\ORM\FieldType\DBEnum
   Float:
@@ -36,6 +38,8 @@ SilverStripe\Core\Injector\Injector:
     class: SilverStripe\ORM\FieldType\DBHTMLVarchar
   Int:
     class: SilverStripe\ORM\FieldType\DBInt
+  IP:
+    class: SilverStripe\ORM\FieldType\DBIp
   BigInt:
     class: SilverStripe\ORM\FieldType\DBBigInt
   Locale:
@@ -58,6 +62,8 @@ SilverStripe\Core\Injector\Injector:
     class: SilverStripe\ORM\FieldType\DBText
   Time:
     class: SilverStripe\ORM\FieldType\DBTime
+  URL:
+    class: SilverStripe\ORM\FieldType\DBUrl
   Varchar:
     class: SilverStripe\ORM\FieldType\DBVarchar
   Year:

bin/sake

@@ -2,6 +2,7 @@
 <?php
 
 use SilverStripe\Cli\Sake;
+use SilverStripe\ORM\DB;
 
 // Ensure that people can't access this from a web-server
 if (!in_array(PHP_SAPI, ['cli', 'cgi', 'cgi-fcgi'])) {
@@ -11,5 +12,8 @@ if (!in_array(PHP_SAPI, ['cli', 'cgi', 'cgi-fcgi'])) {
 
 require_once __DIR__ . '/../src/includes/autoload.php';
 
+// CLI scripts must only use the primary database connection and not replicas
+DB::setMustUsePrimary();
+
 $sake = new Sake();
 $sake->run();

composer.json

@@ -47,6 +47,7 @@
         "symfony/dom-crawler": "^7.0",
         "symfony/filesystem": "^7.0",
         "symfony/http-foundation": "^7.0",
+        "symfony/intl": "^7.0",
         "symfony/mailer": "^7.0",
         "symfony/mime": "^7.0",
         "symfony/translation": "^7.0",

src/Control/Director.php

@@ -17,6 +17,7 @@ use SilverStripe\Versioned\Versioned;
 use SilverStripe\View\Requirements;
 use SilverStripe\View\Requirements_Backend;
 use SilverStripe\View\TemplateGlobalProvider;
+use SilverStripe\ORM\DB;
 
 /**
  * Director is responsible for processing URLs, and providing environment information.
@@ -84,6 +85,14 @@ class Director implements TemplateGlobalProvider
      */
     private static $default_base_url = '`SS_BASE_URL`';
 
+    /**
+     * List of routing rule patterns that must only use the primary database and not a replica
+     */
+    private static array $rule_patterns_must_use_primary_db = [
+        'dev',
+        'Security',
+    ];
+
     public function __construct()
     {
     }
@@ -296,6 +305,18 @@ class Director implements TemplateGlobalProvider
     {
         Injector::inst()->registerService($request, HTTPRequest::class);
 
+        // Check if primary database must be used based on request rules
+        // Note this check must happend before the rules are processed as
+        // $shiftOnSuccess param is passed as true in `$request->match($pattern, true)` later on in
+        // this method, which modifies `$this->dirParts`, thus affecting `$request->match($rule)` directly below
+        $primaryDbOnlyRules = Director::config()->uninherited('rule_patterns_must_use_primary_db');
+        foreach ($primaryDbOnlyRules as $rule) {
+            if ($request->match($rule)) {
+                DB::setMustUsePrimary();
+                break;
+            }
+        }
+
         $rules = Director::config()->uninherited('rules');
 
         $this->extend('updateRules', $rules);

src/Core/ClassInfo.php

@@ -85,7 +85,7 @@ class ClassInfo implements Flushable
     public static function hasTable($tableName)
     {
         $cache = ClassInfo::getCache();
-        $configData = serialize(DB::getConfig());
+        $configData = serialize(DB::getConfig(DB::CONN_PRIMARY));
         $cacheKey = 'tableList_' . md5($configData);
         $tableList = $cache->get($cacheKey) ?? [];
         if (empty($tableList) && DB::is_active()) {

src/Core/CoreKernel.php

@@ -7,12 +7,14 @@ use SilverStripe\Dev\Install\DatabaseAdapterRegistry;
 use SilverStripe\ORM\Connect\NullDatabase;
 use SilverStripe\ORM\DB;
 use Exception;
+use InvalidArgumentException;
 
 /**
  * Simple Kernel container
  */
 class CoreKernel extends BaseKernel
 {
+
     protected bool $bootDatabase = true;
 
     /**
@@ -38,7 +40,7 @@ class CoreKernel extends BaseKernel
         $this->flush = $flush;
 
         if (!$this->bootDatabase) {
-            DB::set_conn(new NullDatabase());
+            DB::set_conn(new NullDatabase(), DB::CONN_PRIMARY);
         }
 
         $this->bootPHP();
@@ -73,7 +75,7 @@ class CoreKernel extends BaseKernel
     }
 
     /**
-     * Load default database configuration from the $database and $databaseConfig globals
+     * Load database configuration from the $database and $databaseConfig globals
      */
     protected function bootDatabaseGlobals()
     {
@@ -84,41 +86,62 @@ class CoreKernel extends BaseKernel
         global $databaseConfig;
         global $database;
 
-        // Case 1: $databaseConfig global exists. Merge $database in as needed
-        if (!empty($databaseConfig)) {
-            if (!empty($database)) {
+        // Ensure global database config has prefix and suffix applied
+        if (!empty($databaseConfig) && !empty($database)) {
             $databaseConfig['database'] = $this->getDatabasePrefix() . $database . $this->getDatabaseSuffix();
         }
 
-            // Only set it if its valid, otherwise ignore $databaseConfig entirely
-            if (!empty($databaseConfig['database'])) {
-                DB::setConfig($databaseConfig);
+        // Set config for primary and any replicas
+        for ($i = 0; $i <= DB::MAX_REPLICAS; $i++) {
+            if ($i === 0) {
+                $name = DB::CONN_PRIMARY;
+            } else {
+                $name = DB::getReplicaConfigKey($i);
+                if (!DB::hasConfig($name)) {
+                    break;
+                }
+            }
 
+            // Case 1: $databaseConfig global exists
+            // Only set it if its valid, otherwise ignore $databaseConfig entirely
+            if (!empty($databaseConfig) && !empty($databaseConfig['database'])) {
+                DB::setConfig($databaseConfig, $name);
                 return;
             }
-        }
 
-        // Case 2: $database merged into existing config
+            // Case 2: $databaseConfig global does not exist
+            // Merge $database global into existing config
             if (!empty($database)) {
-            $existing = DB::getConfig();
-            $existing['database'] = $this->getDatabasePrefix() . $database . $this->getDatabaseSuffix();
-
-            DB::setConfig($existing);
+                $dbConfig = DB::getConfig($name);
+                $dbConfig['database'] = $this->getDatabasePrefix() . $database . $this->getDatabaseSuffix();
+                DB::setConfig($dbConfig, $name);
+            }
         }
     }
 
     /**
-     * Load default database configuration from environment variable
+     * Load database configuration from environment variables
      */
     protected function bootDatabaseEnvVars()
     {
         if (!$this->bootDatabase) {
             return;
         }
-        // Set default database config
+        // Set primary database config
         $databaseConfig = $this->getDatabaseConfig();
         $databaseConfig['database'] = $this->getDatabaseName();
-        DB::setConfig($databaseConfig);
+        DB::setConfig($databaseConfig, DB::CONN_PRIMARY);
+
+        // Set database replicas config
+        for ($i = 1; $i <= DB::MAX_REPLICAS; $i++) {
+            $envKey = $this->getReplicaEnvKey('SS_DATABASE_SERVER', $i);
+            if (!Environment::hasEnv($envKey)) {
+                break;
+            }
+            $replicaDatabaseConfig = $this->getDatabaseReplicaConfig($i);
+            $configKey = DB::getReplicaConfigKey($i);
+            DB::setConfig($replicaDatabaseConfig, $configKey);
+        }
     }
 
     /**
@@ -127,12 +150,72 @@ class CoreKernel extends BaseKernel
      * @return array
      */
     protected function getDatabaseConfig()
+    {
+        return $this->getSingleDataBaseConfig(0);
+    }
+
+    private function getDatabaseReplicaConfig(int $replica)
+    {
+        if ($replica <= 0) {
+            throw new InvalidArgumentException('Replica number must be greater than 0');
+        }
+        return $this->getSingleDataBaseConfig($replica);
+    }
+
+    /**
+     * Convert a database key to a replica key
+     * e.g. SS_DATABASE_SERVER -> SS_DATABASE_SERVER_REPLICA_01
+     *
+     * @param string $key - The key to look up in the environment
+     * @param int $replica - Replica number
+     */
+    private function getReplicaEnvKey(string $key, int $replica): string
+    {
+        if ($replica <= 0) {
+            throw new InvalidArgumentException('Replica number must be greater than 0');
+        }
+        // Do not allow replicas to define keys that could lead to unexpected behaviour if
+        // they do not match the primary database configuration
+        if (in_array($key, ['SS_DATABASE_CLASS', 'SS_DATABASE_NAME', 'SS_DATABASE_CHOOSE_NAME'])) {
+            return $key;
+        }
+        // Left pad replica number with a zeros to match the length of the maximum replica number
+        $len = strlen((string) DB::MAX_REPLICAS);
+        return $key . '_REPLICA_' . str_pad($replica, $len, '0', STR_PAD_LEFT);
+    }
+
+    /**
+     * Reads a single database configuration variable from the environment
+     * For replica databases, it will first attempt to find replica-specific configuration
+     * before falling back to the primary configuration.
+     *
+     * Replicate specific configuration has `_REPLICA_01` appended to the key
+     * where 01 is the replica number.
+     *
+     * @param string $key - The key to look up in the environment
+     * @param int $replica - Replica number. Passing 0 will return the primary database configuration
+     */
+    private function getDatabaseConfigVariable(string $key, int $replica): string
+    {
+        if ($replica > 0) {
+            $key = $this->getReplicaEnvKey($key, $replica);
+        }
+        if (Environment::hasEnv($key)) {
+            return Environment::getEnv($key);
+        }
+        return '';
+    }
+
+    /**
+     * @param int $replica - Replica number. Passing 0 will return the primary database configuration
+     */
+    private function getSingleDataBaseConfig(int $replica): array
     {
         $databaseConfig = [
-            "type" => Environment::getEnv('SS_DATABASE_CLASS') ?: 'MySQLDatabase',
-            "server" => Environment::getEnv('SS_DATABASE_SERVER') ?: 'localhost',
-            "username" => Environment::getEnv('SS_DATABASE_USERNAME') ?: null,
-            "password" => Environment::getEnv('SS_DATABASE_PASSWORD') ?: null,
+            "type" => $this->getDatabaseConfigVariable('SS_DATABASE_CLASS', $replica) ?: 'MySQLDatabase',
+            "server" => $this->getDatabaseConfigVariable('SS_DATABASE_SERVER', $replica) ?: 'localhost',
+            "username" => $this->getDatabaseConfigVariable('SS_DATABASE_USERNAME', $replica) ?: null,
+            "password" => $this->getDatabaseConfigVariable('SS_DATABASE_PASSWORD', $replica) ?: null,
         ];
 
         // Only add SSL keys in the array if there is an actual value associated with them
@@ -143,7 +226,7 @@ class CoreKernel extends BaseKernel
             'ssl_cipher' => 'SS_DATABASE_SSL_CIPHER',
         ];
         foreach ($sslConf as $key => $envVar) {
-            $envValue = Environment::getEnv($envVar);
+            $envValue = $this->getDatabaseConfigVariable($envVar, $replica);
             if ($envValue) {
                 $databaseConfig[$key] = $envValue;
             }
@@ -159,25 +242,25 @@ class CoreKernel extends BaseKernel
         }
 
         // Set the port if called for
-        $dbPort = Environment::getEnv('SS_DATABASE_PORT');
+        $dbPort = $this->getDatabaseConfigVariable('SS_DATABASE_PORT', $replica);
         if ($dbPort) {
             $databaseConfig['port'] = $dbPort;
         }
 
         // Set the timezone if called for
-        $dbTZ = Environment::getEnv('SS_DATABASE_TIMEZONE');
+        $dbTZ = $this->getDatabaseConfigVariable('SS_DATABASE_TIMEZONE', $replica);
         if ($dbTZ) {
             $databaseConfig['timezone'] = $dbTZ;
         }
 
         // For schema enabled drivers:
-        $dbSchema = Environment::getEnv('SS_DATABASE_SCHEMA');
+        $dbSchema = $this->getDatabaseConfigVariable('SS_DATABASE_SCHEMA', $replica);
         if ($dbSchema) {
             $databaseConfig["schema"] = $dbSchema;
         }
 
         // For SQlite3 memory databases (mainly for testing purposes)
-        $dbMemory = Environment::getEnv('SS_DATABASE_MEMORY');
+        $dbMemory = $this->getDatabaseConfigVariable('SS_DATABASE_MEMORY', $replica);
         if ($dbMemory) {
             $databaseConfig["memory"] = $dbMemory;
         }
@@ -205,6 +288,7 @@ class CoreKernel extends BaseKernel
 
     /**
      * Get name of database
+     * Note that any replicas must have the same database name as the primary database
      *
      * @return string
      */

src/Core/Validation/ConstraintValidator.php

@@ -35,9 +35,9 @@ class ConstraintValidator
         /** @var ConstraintViolationInterface $violation */
         foreach ($violations as $violation) {
             if ($fieldName) {
-                $result->addFieldError($fieldName, $violation->getMessage());
+                $result->addFieldError($fieldName, $violation->getMessage(), value: $value);
             } else {
-                $result->addError($violation->getMessage());
+                $result->addError($violation->getMessage(), value: $value);
             }
         }
 

src/Core/Validation/FieldValidation/AbstractSymfonyFieldValidator.php

@@ -0,0 +1,48 @@
+<?php
+
+namespace SilverStripe\Core\Validation\FieldValidation;
+
+use SilverStripe\Core\Validation\ValidationResult;
+use SilverStripe\Core\Validation\ConstraintValidator;
+use SilverStripe\Core\Validation\FieldValidation\StringFieldValidator;
+
+/**
+ * Abstract class for validators that use Symfony constraints
+ */
+abstract class AbstractSymfonyFieldValidator extends StringFieldValidator
+{
+    protected function validateValue(): ValidationResult
+    {
+        $result = parent::validateValue();
+        if (!$result->isValid()) {
+            return $result;
+        }
+        $constraintClass = $this->getConstraintClass();
+        $args = [
+            ...$this->getContraintNamedArgs(),
+            'message' => $this->getMessage(),
+        ];
+        $constraint = new $constraintClass(...$args);
+        $validationResult = ConstraintValidator::validate($this->value, $constraint, $this->name);
+        return $result->combineAnd($validationResult);
+    }
+
+    /**
+     * The symfony constraint class to use
+     */
+    abstract protected function getConstraintClass(): string;
+
+    /**
+     * The named args to pass to the constraint
+     * Defined named args as assoc array keys
+     */
+    protected function getContraintNamedArgs(): array
+    {
+        return [];
+    }
+
+    /**
+     * The message to use when the value is invalid
+     */
+    abstract protected function getMessage(): string;
+}

src/Core/Validation/FieldValidation/BigIntFieldValidator.php

@@ -0,0 +1,36 @@
+<?php
+
+namespace SilverStripe\Core\Validation\FieldValidation;
+
+use SilverStripe\Core\Validation\FieldValidation\IntFieldValidator;
+
+class BigIntFieldValidator extends IntFieldValidator
+{
+    /**
+     * The minimum value for a signed 64-bit integer.
+     * Defined as string instead of int otherwise will end up as a float
+     * on 64-bit systems if defined as an int
+     */
+    private const MIN_64_BIT_INT = '-9223372036854775808';
+
+    /**
+     * The maximum value for a signed 64-bit integer.
+     */
+    private const MAX_64_BIT_INT = '9223372036854775807';
+
+    public function __construct(
+        string $name,
+        mixed $value,
+        ?int $minValue = null,
+        ?int $maxValue = null
+    ) {
+        if (is_null($minValue)) {
+            // Casting the string const to an int will properly return an int on 64-bit systems
+            $minValue = (int) BigIntFieldValidator::MIN_64_BIT_INT;
+        }
+        if (is_null($maxValue)) {
+            $maxValue = (int) BigIntFieldValidator::MAX_64_BIT_INT;
+        }
+        parent::__construct($name, $value, $minValue, $maxValue);
+    }
+}

src/Core/Validation/FieldValidation/BooleanFieldValidator.php

@@ -0,0 +1,23 @@
+<?php
+
+namespace SilverStripe\Core\Validation\FieldValidation;
+
+use SilverStripe\Core\Validation\ValidationResult;
+use SilverStripe\Core\Validation\FieldValidation\FieldValidator;
+
+/**
+ * Validates value is boolean stored as an integer i.e. 1 or 0
+ * true and false are not valid values
+ */
+class BooleanFieldValidator extends FieldValidator
+{
+    protected function validateValue(): ValidationResult
+    {
+        $result = ValidationResult::create();
+        if ($this->value !== true && $this->value !== false) {
+            $message = _t(__CLASS__ . '.INVALID', 'Invalid value');
+            $result->addFieldError($this->name, $message, value: $this->value);
+        }
+        return $result;
+    }
+}

src/Core/Validation/FieldValidation/CompositeFieldValidator.php

@@ -0,0 +1,33 @@
+<?php
+
+namespace SilverStripe\Core\Validation\FieldValidation;
+
+use InvalidArgumentException;
+use SilverStripe\Core\Validation\ValidationResult;
+use SilverStripe\Core\Validation\FieldValidation\FieldValidator;
+use SilverStripe\Core\Validation\FieldValidation\FieldValidationInterface;
+
+class CompositeFieldValidator extends FieldValidator
+{
+    public function __construct(string $name, mixed $value)
+    {
+        parent::__construct($name, $value);
+        if (!is_iterable($value)) {
+            throw new InvalidArgumentException('Value must be iterable');
+        }
+        foreach ($value as $child) {
+            if (!is_a($child, FieldValidationInterface::class)) {
+                throw new InvalidArgumentException('Child is not a' . FieldValidationInterface::class);
+            }
+        }
+    }
+
+    protected function validateValue(): ValidationResult
+    {
+        $result = ValidationResult::create();
+        foreach ($this->value as $child) {
+            $result->combineAnd($child->validate());
+        }
+        return $result;
+    }
+}

src/Core/Validation/FieldValidation/DateFieldValidator.php

@@ -0,0 +1,40 @@
+<?php
+
+namespace SilverStripe\Core\Validation\FieldValidation;
+
+use SilverStripe\Core\Validation\FieldValidation\FieldValidator;
+use SilverStripe\Core\Validation\ValidationResult;
+
+/**
+ * Validates that a value is a valid date, which means that it follows the equivalent formats:
+ * - PHP date format Y-m-d
+ * - SO format y-MM-dd i.e. DBDate::ISO_DATE
+ * Emtpy values are allowed
+ */
+class DateFieldValidator extends FieldValidator
+{
+    protected function validateValue(): ValidationResult
+    {
+        $result = ValidationResult::create();
+        // Allow empty values
+        if (!$this->value) {
+            return $result;
+        }
+        // Not using symfony/validator because it was allowing d-m-Y format strings
+        $date = date_parse_from_format($this->getFormat(), $this->value ?? '');
+        if ($date === false || $date['error_count'] > 0 || $date['warning_count'] > 0) {
+            $result->addFieldError($this->name, $this->getMessage());
+        }
+        return $result;
+    }
+
+    protected function getFormat(): string
+    {
+        return 'Y-m-d';
+    }
+
+    protected function getMessage(): string
+    {
+        return _t(__CLASS__ . '.INVALID', 'Invalid date');
+    }
+}

src/Core/Validation/FieldValidation/DatetimeFieldValidator.php

@@ -0,0 +1,23 @@
+<?php
+
+namespace SilverStripe\Core\Validation\FieldValidation;
+
+use SilverStripe\Core\Validation\FieldValidation\DateFieldValidator;
+
+/**
+ * Validates that a value is a valid date/time, which means that it follows the equivalent formats:
+ * - PHP date format Y-m-d H:i:s
+ * - ISO format 'y-MM-dd HH:mm:ss' i.e. DBDateTime::ISO_DATETIME
+ */
+class DatetimeFieldValidator extends DateFieldValidator
+{
+    protected function getFormat(): string
+    {
+        return 'Y-m-d H:i:s';
+    }
+
+    protected function getMessage(): string
+    {
+        return _t(__CLASS__ . '.INVALID', 'Invalid date/time');
+    }
+}

src/Core/Validation/FieldValidation/DecimalFieldValidator.php

@@ -0,0 +1,65 @@
+<?php
+
+namespace SilverStripe\Core\Validation\FieldValidation;
+
+use SilverStripe\Core\Validation\ValidationResult;
+use SilverStripe\Core\Validation\FieldValidation\NumericFieldValidator;
+
+class DecimalFieldValidator extends NumericFieldValidator
+{
+    /**
+     * Whole number size e.g. For Decimal(9,2) this would be 9
+     */
+    private int $wholeSize;
+
+    /**
+     * Decimal size e.g. For Decimal(5,2) this would be 2
+     */
+    private int $decimalSize;
+
+    public function __construct(string $name, mixed $value, int $wholeSize, int $decimalSize)
+    {
+        parent::__construct($name, $value);
+        $this->wholeSize = $wholeSize;
+        $this->decimalSize = $decimalSize;
+    }
+
+    protected function validateValue(): ValidationResult
+    {
+        $result = parent::validateValue();
+        if (!$result->isValid()) {
+            return $result;
+        }
+        // Example of how digits are stored in the database
+        // Decimal(5,2) is allowed a total of 5 digits, and will always round to 2 decimal places
+        // This means it has a maximum 3 digits before the decimal point
+        //
+        // Valid
+        // 123.99
+        // 999.99
+        // -999.99
+        // 123.999 - will round to 124.00
+        //
+        // Not valid
+        // 1234.9 - 4 digits the before the decimal point
+        // 999.999 - would be rounted to 10000000.00 which exceeds the 9 digits
+        
+        // Convert to absolute value - any the minus sign is not counted
+        $absValue = abs($this->value);
+        // Round to the decimal size which is what the database will do
+        $rounded = round($absValue, $this->decimalSize);
+        // Get formatted as a string, which will right pad with zeros to the decimal size
+        $rounded = number_format($rounded, $this->decimalSize, thousands_separator: '');
+        // Count this number of digits - the minus 1 is for the decimal point
+        $digitCount = strlen((string) $rounded) - 1;
+        if ($digitCount > $this->wholeSize) {
+            $message = _t(
+                __CLASS__ . '.TOOLARGE',
+                'Digit count cannot be greater than than {wholeSize}',
+                ['wholeSize' => $this->wholeSize]
+            );
+            $result->addFieldError($this->name, $message, value: $this->value);
+        }
+        return $result;
+    }
+}

src/Core/Validation/FieldValidation/EmailFieldValidator.php

@@ -0,0 +1,19 @@
+<?php
+
+namespace SilverStripe\Core\Validation\FieldValidation;
+
+use Symfony\Component\Validator\Constraints;
+use SilverStripe\Core\Validation\FieldValidation\AbstractSymfonyFieldValidator;
+
+class EmailFieldValidator extends AbstractSymfonyFieldValidator
+{
+    protected function getConstraintClass(): string
+    {
+        return Constraints\Email::class;
+    }
+
+    protected function getMessage(): string
+    {
+        return _t(__CLASS__ . '.INVALID', 'Invalid email address');
+    }
+}

src/Core/Validation/FieldValidation/EnumFieldValidator.php

@@ -0,0 +1,31 @@
+<?php
+
+namespace SilverStripe\Core\Validation\FieldValidation;
+
+use SilverStripe\Core\Validation\ValidationResult;
+use SilverStripe\Core\Validation\FieldValidation\FieldValidator;
+
+class EnumFieldValidator extends FieldValidator
+{
+    protected array $allowedValues;
+
+    public function __construct(string $name, mixed $value, array $allowedValues)
+    {
+        parent::__construct($name, $value);
+        $this->allowedValues = $allowedValues;
+    }
+
+    protected function validateValue(): ValidationResult
+    {
+        $result = ValidationResult::create();
+        // Allow empty strings
+        if ($this->value === '') {
+            return $result;
+        }
+        if (!in_array($this->value, $this->allowedValues, true)) {
+            $message = _t(__CLASS__ . '.NOTALLOWED', 'Not an allowed value');
+            $result->addFieldError($this->name, $message, value: $this->value);
+        }
+        return $result;
+    }
+}

src/Core/Validation/FieldValidation/FieldValidationInterface.php

@@ -0,0 +1,12 @@
+<?php
+
+namespace SilverStripe\Core\Validation\FieldValidation;
+
+use SilverStripe\Core\Validation\ValidationInterface;
+
+interface FieldValidationInterface extends ValidationInterface
+{
+    public function getName(): string;
+
+    public function getValueForValidation(): mixed;
+}

src/Core/Validation/FieldValidation/FieldValidator.php

@@ -0,0 +1,39 @@
+<?php
+
+namespace SilverStripe\Core\Validation\FieldValidation;
+
+use SilverStripe\Core\Validation\ValidationResult;
+use SilverStripe\Core\Validation\ValidationInterface;
+
+/**
+ * Abstract class that can be used as a validator for FormFields and DBFields
+ */
+abstract class FieldValidator implements ValidationInterface
+{
+    protected string $name;
+    protected mixed $value;
+
+    public function __construct(string $name, mixed $value)
+    {
+        $this->name = $name;
+        $this->value = $value;
+    }
+
+    /**
+     * Validate the value
+     */
+    public function validate(): ValidationResult
+    {
+        $result = ValidationResult::create();
+        $validationResult = $this->validateValue($result);
+        if (!$validationResult->isValid()) {
+            $result->combineAnd($validationResult);
+        }
+        return $result;
+    }
+
+    /**
+     * Inner validatation method that that is implemented by subclasses
+     */
+    abstract protected function validateValue(): ValidationResult;
+}

src/Core/Validation/FieldValidation/FieldValidatorsTrait.php

@@ -0,0 +1,118 @@
+<?php
+
+namespace SilverStripe\Core\Validation\FieldValidation;
+
+use RuntimeException;
+use SilverStripe\Core\Injector\Injector;
+use SilverStripe\Core\Config\Configurable;
+use SilverStripe\Core\Validation\FieldValidation\FieldValidationInterface;
+use SilverStripe\Core\Validation\ValidationResult;
+use SilverStripe\Forms\FormField;
+
+trait FieldValidatorsTrait
+{
+    /**
+     * FieldValidators configuration for the field, which is either a FormField or DBField
+     *
+     * Each item in the array can be one of the following
+     * a) MyFieldValidator::class,
+     * b) MyFieldValidator::class => [null, 'getMyArg'],
+     * c) MyFieldValidator::class => null,
+     *
+     * a) Will create a FieldValidator and pass the name and value of the field as args to the constructor
+     * b) Will create a FieldValidator and pass the name, value, make a pass additional args, calling each
+     *    non-null value on the field e.g. it will skip the first arg and call $field->getMyArg() for the second arg
+     * c) Will disable a previously set FieldValidator. This is useful to disable a FieldValidator that was set
+     *    on a parent class
+     *
+     * You may only have a single instance of a FieldValidator class per field
+     */
+    private static array $field_validators = [];
+
+    /**
+     * Validate this field
+     */
+    public function validate(): ValidationResult
+    {
+        $result = ValidationResult::create();
+        $fieldValidators = $this->getFieldValidators();
+        foreach ($fieldValidators as $fieldValidator) {
+            $validationResult = $fieldValidator->validate();
+            if (!$validationResult->isValid()) {
+                $result->combineAnd($validationResult);
+            }
+        }
+        return $result;
+    }
+
+    /**
+     * Get FieldValidators based on `field_validators` configuration
+     */
+    private function getFieldValidators(): array
+    {
+        $fieldValidators = [];
+        // Used to disable a validator that was previously set with an int index
+        $disabledClasses = [];
+        $interface = FieldValidationInterface::class;
+        // temporary check, will make FormField implement FieldValidationInterface in a future PR
+        $tmp = FormField::class;
+        if (!is_a($this, $interface) && !is_a($this, $tmp)) {
+            $class = get_class($this);
+            throw new RuntimeException("Class $class does not implement interface $interface");
+        }
+        /** @var FieldValidationInterface|Configurable $this */
+        $name = $this->getName();
+        $value = $this->getValueForValidation();
+        // Field name is required for FieldValidators when called ValidationResult::addFieldMessage()
+        if ($name === '') {
+            throw new RuntimeException('Field name is blank');
+        }
+        $classes = [];
+        $config = $this->config()->get('field_validators');
+        foreach ($config as $indexOrClass => $classOrArgCallsOrDisable) {
+            $class = '';
+            $argCalls = [];
+            $disable = false;
+            if (is_int($indexOrClass)) {
+                $class = $classOrArgCallsOrDisable;
+            } else {
+                $class = $indexOrClass;
+                $argCalls = $classOrArgCallsOrDisable;
+                $disable = $classOrArgCallsOrDisable === null;
+            }
+            if ($disable) {
+                $disabledClasses[$class] = true;
+                continue;
+            } else {
+                if (isset($disabledClasses[$class])) {
+                    unset($disabledClasses[$class]);
+                }
+            }
+            if (!is_a($class, FieldValidator::class, true)) {
+                throw new RuntimeException("Class $class is not a FieldValidator");
+            }
+            if (!is_array($argCalls)) {
+                throw new RuntimeException("argCalls for FieldValidator $class is not an array");
+            }
+            $classes[$class] = $argCalls;
+        }
+        foreach (array_keys($disabledClasses) as $class) {
+            unset($classes[$class]);
+        }
+        foreach ($classes as $class => $argCalls) {
+            $args = [$name, $value];
+            foreach ($argCalls as $i => $argCall) {
+                if (!is_string($argCall) && !is_null($argCall)) {
+                    throw new RuntimeException("argCall $i for FieldValidator $class is not a string or null");
+                }
+                if ($argCall) {
+                    $args[] = call_user_func([$this, $argCall]);
+                } else {
+                    $args[] = null;
+                }
+            }
+            $fieldValidators[$class] = Injector::inst()->createWithArgs($class, $args);
+        }
+        return array_values($fieldValidators);
+    }
+}

src/Core/Validation/FieldValidation/IntFieldValidator.php

@@ -0,0 +1,46 @@
+<?php
+
+namespace SilverStripe\Core\Validation\FieldValidation;
+
+use SilverStripe\Core\Validation\ValidationResult;
+use SilverStripe\Core\Validation\FieldValidation\NumericFieldValidator;
+
+class IntFieldValidator extends NumericFieldValidator
+{
+    /**
+     * The minimum value for a signed 32-bit integer.
+     * Defined as string instead of int because be cast to a float
+     * on 32-bit systems if defined as an int
+     */
+    private const MIN_32_BIT_INT = '-2147483648';
+
+    /**
+     * The maximum value for a signed 32-bit integer.
+     */
+    private const MAX_32_BIT_INT = '2147483647';
+
+    public function __construct(
+        string $name,
+        mixed $value,
+        ?int $minValue = null,
+        ?int $maxValue = null
+    ) {
+        if (is_null($minValue)) {
+            $minValue = (int) IntFieldValidator::MIN_32_BIT_INT;
+        }
+        if (is_null($maxValue)) {
+            $maxValue = (int) IntFieldValidator::MAX_32_BIT_INT;
+        }
+        parent::__construct($name, $value, $minValue, $maxValue);
+    }
+
+    protected function validateValue(): ValidationResult
+    {
+        $result = parent::validateValue();
+        if (!is_int($this->value)) {
+            $message = _t(__CLASS__ . '.WRONGTYPE', 'Must be an integer');
+            $result->addFieldError($this->name, $message, value: $this->value);
+        }
+        return $result;
+    }
+}

src/Core/Validation/FieldValidation/IpFieldValidator.php

@@ -0,0 +1,30 @@
+<?php
+
+namespace SilverStripe\Core\Validation\FieldValidation;
+
+use Symfony\Component\Validator\Constraints;
+use SilverStripe\Core\Validation\FieldValidation\AbstractSymfonyFieldValidator;
+
+/**
+ * Validator for IP addresses. Accepts both IPv4 and IPv6.
+ */
+class IpFieldValidator extends AbstractSymfonyFieldValidator
+{
+    protected function getConstraintClass(): string
+    {
+        return Constraints\Ip::class;
+    }
+
+    protected function getContraintNamedArgs(): array
+    {
+        return [
+            // Allow both IPv4 and IPv6
+            'version' => Constraints\Ip::ALL,
+        ];
+    }
+
+    protected function getMessage(): string
+    {
+        return _t(__CLASS__ . '.INVALID', 'Invalid IP address');
+    }
+}

src/Core/Validation/FieldValidation/LocaleFieldValidator.php

@@ -0,0 +1,22 @@
+<?php
+
+namespace SilverStripe\Core\Validation\FieldValidation;
+
+use Symfony\Component\Validator\Constraints;
+use SilverStripe\Core\Validation\FieldValidation\AbstractSymfonyFieldValidator;
+
+/**
+ * Validates that a value is a valid locale, e.g. de, de_DE)
+ */
+class LocaleFieldValidator extends AbstractSymfonyFieldValidator
+{
+    protected function getConstraintClass(): string
+    {
+        return Constraints\Locale::class;
+    }
+
+    protected function getMessage(): string
+    {
+        return _t(__CLASS__ . '.INVALID', 'Invalid locale');
+    }
+}

src/Core/Validation/FieldValidation/MultiEnumFieldValidator.php

@@ -0,0 +1,31 @@
+<?php
+
+namespace SilverStripe\Core\Validation\FieldValidation;
+
+use InvalidArgumentException;
+use SilverStripe\Core\Validation\ValidationResult;
+use SilverStripe\Core\Validation\FieldValidation\EnumFieldValidator;
+
+class MultiEnumFieldValidator extends EnumFieldValidator
+{
+    public function __construct(string $name, mixed $value, array $allowedValues)
+    {
+        if (!is_array($value)) {
+            throw new InvalidArgumentException('Value must be an array');
+        }
+        parent::__construct($name, $value, $allowedValues);
+    }
+
+    protected function validateValue(): ValidationResult
+    {
+        $result = ValidationResult::create();
+        foreach ($this->value as $value) {
+            if (!in_array($value, $this->allowedValues, true)) {
+                $message = _t(__CLASS__ . '.NOTALLOWED', 'Not an allowed value');
+                $result->addFieldError($this->name, $message, value: $value);
+                break;
+            }
+        }
+        return $result;
+    }
+}

src/Core/Validation/FieldValidation/NumericFieldValidator.php

@@ -0,0 +1,56 @@
+<?php
+
+namespace SilverStripe\Core\Validation\FieldValidation;
+
+use SilverStripe\Core\Validation\ValidationResult;
+use SilverStripe\Core\Validation\FieldValidation\FieldValidator;
+
+class NumericFieldValidator extends FieldValidator
+{
+    /**
+     * Minimum size of the number
+     */
+    private ?int $minValue;
+
+    /**
+     * Maximum size of the number
+     */
+    private ?int $maxValue;
+
+    public function __construct(
+        string $name,
+        mixed $value,
+        ?int $minValue = null,
+        ?int $maxValue = null
+    ) {
+        $this->minValue = $minValue;
+        $this->maxValue = $maxValue;
+        parent::__construct($name, $value);
+    }
+
+    protected function validateValue(): ValidationResult
+    {
+        $result = ValidationResult::create();
+        if (!is_numeric($this->value) || is_string($this->value)) {
+            // Must be a numeric value, though not as a numeric string
+            $message = _t(__CLASS__ . '.WRONGTYPE', 'Must be numeric');
+            $result->addFieldError($this->name, $message, value: $this->value);
+            return $result;
+        } elseif (isset($this->minValue) && $this->value < $this->minValue) {
+            $message = _t(
+                __CLASS__ . '.TOOSMALL',
+                'Value cannot be less than {minValue}',
+                ['minValue' => $this->minValue]
+            );
+            $result->addFieldError($this->name, $message, value: $this->value);
+        } elseif (isset($this->maxValue) && $this->value > $this->maxValue) {
+            $message = _t(
+                __CLASS__ . '.TOOLARGE',
+                'Value cannot be greater than {maxValue}',
+                ['maxValue' => $this->maxValue]
+            );
+            $result->addFieldError($this->name, $message, value: $this->value);
+        }
+        return $result;
+    }
+}

src/Core/Validation/FieldValidation/StringFieldValidator.php

@@ -0,0 +1,69 @@
+<?php
+
+namespace SilverStripe\Core\Validation\FieldValidation;
+
+use InvalidArgumentException;
+use SilverStripe\Core\Validation\ValidationResult;
+use SilverStripe\Core\Validation\FieldValidation\FieldValidator;
+
+/**
+ * Validates that a value is a string and optionally checks its multi-byte length.
+ */
+class StringFieldValidator extends FieldValidator
+{
+    /**
+     * The minimum length of the string
+     */
+    private ?int $minLength;
+
+    /**
+     * The maximum length of the string
+     */
+    private ?int $maxLength;
+
+    public function __construct(
+        string $name,
+        mixed $value,
+        ?int $minLength = null,
+        ?int $maxLength = null
+    ) {
+        parent::__construct($name, $value);
+        if ($minLength && $minLength < 0) {
+            throw new InvalidArgumentException('minLength must be greater than or equal to 0');
+        }
+        $this->minLength = $minLength;
+        $this->maxLength = $maxLength;
+    }
+
+    protected function validateValue(): ValidationResult
+    {
+        $result = ValidationResult::create();
+        if (!is_string($this->value)) {
+            $message = _t(__CLASS__ . '.WRONGTYPE', 'Must be a string');
+            $result->addFieldError($this->name, $message, value: $this->value);
+            return $result;
+        }
+        // Blank strings are valid, even if there's a minLength requirement
+        if ($this->value === '') {
+            return $result;
+        }
+        $len = mb_strlen($this->value);
+        if (!is_null($this->minLength) && $len < $this->minLength) {
+            $message = _t(
+                __CLASS__ . '.TOOSHORT',
+                'Must have at least {minLength} characters',
+                ['minLength' => $this->minLength]
+            );
+            $result->addFieldError($this->name, $message, value: $this->value);
+        }
+        if (!is_null($this->maxLength) && $len > $this->maxLength) {
+            $message = _t(
+                __CLASS__ . '.TOOLONG',
+                'Can not have more than {maxLength} characters',
+                ['maxLength' => $this->maxLength]
+            );
+            $result->addFieldError($this->name, $message, value: $this->value);
+        }
+        return $result;
+    }
+}

src/Core/Validation/FieldValidation/TimeFieldValidator.php

@@ -0,0 +1,23 @@
+<?php
+
+namespace SilverStripe\Core\Validation\FieldValidation;
+
+use SilverStripe\Core\Validation\FieldValidation\DateFieldValidator;
+
+/**
+ * Validates that a value is a valid time, which means that it follows the equivalent formats:
+ * - PHP date format H:i:s
+ * - ISO format 'HH:mm:ss' i.e. DBTime::ISO_TIME
+ */
+class TimeFieldValidator extends DateFieldValidator
+{
+    protected function getFormat(): string
+    {
+        return 'H:i:s';
+    }
+
+    protected function getMessage(): string
+    {
+        return _t(__CLASS__ . '.INVALID', 'Invalid time');
+    }
+}

src/Core/Validation/FieldValidation/UrlFieldValidator.php

@@ -0,0 +1,19 @@
+<?php
+
+namespace SilverStripe\Core\Validation\FieldValidation;
+
+use Symfony\Component\Validator\Constraints;
+use SilverStripe\Core\Validation\FieldValidation\AbstractSymfonyFieldValidator;
+
+class UrlFieldValidator extends AbstractSymfonyFieldValidator
+{
+    protected function getConstraintClass(): string
+    {
+        return Constraints\Url::class;
+    }
+
+    protected function getMessage(): string
+    {
+        return _t(__CLASS__ . '.INVALID', 'Invalid URL');
+    }
+}

src/Core/Validation/FieldValidation/YearFieldValidator.php

@@ -0,0 +1,42 @@
+<?php
+
+namespace SilverStripe\Core\Validation\FieldValidation;
+
+use SilverStripe\Core\Validation\ValidationResult;
+use SilverStripe\Core\Validation\FieldValidation\NumericFieldValidator;
+
+/**
+ * Validates that a field is an integer year between two dates, or 0 for a null value.
+ */
+class YearFieldValidator extends IntFieldValidator
+{
+    private ?int $minValue;
+
+    public function __construct(
+        string $name,
+        mixed $value,
+        ?int $minValue = null,
+        ?int $maxValue = null
+    ) {
+        $this->minValue = $minValue;
+        parent::__construct($name, $value, 0, $maxValue);
+    }
+
+    protected function validateValue(): ValidationResult
+    {
+        $result = parent::validateValue();
+        if ($this->value === 0) {
+            return $result;
+        }
+        if ($this->minValue && $this->value < $this->minValue) {
+            // Uses the same translation key as NumericFieldValidator
+            $message = _t(
+                NumericFieldValidator::class . '.TOOSMALL',
+                'Value cannot be less than {minValue}',
+                ['minValue' => $this->minValue]
+            );
+            $result->addFieldError($this->name, $message, value: $this->value);
+        }
+        return $result;
+    }
+}

src/Core/Validation/ValidationInterface.php

@@ -0,0 +1,10 @@
+<?php
+
+namespace SilverStripe\Core\Validation;
+
+use SilverStripe\Core\Validation\ValidationResult;
+
+interface ValidationInterface
+{
+    public function validate(): ValidationResult;
+}

src/Core/Validation/ValidationResult.php

@@ -46,6 +46,11 @@ class ValidationResult
      */
     const CAST_TEXT = 'text';
 
+    /**
+     * Default value of $value parameter
+     */
+    private const VALUE_UNSET = '_VALUE_UNSET_';
+
     /**
      * Is the result valid or not.
      * Note that there can be non-error messages in the list.
@@ -71,11 +76,17 @@ class ValidationResult
      *                            This can be usedful for ensuring no duplicate messages
      * @param string|bool $cast Cast type; One of the CAST_ constant definitions.
      * Bool values will be treated as plain text flag.
+     * @param mixed $value The value that failed validation
      * @return $this
      */
-    public function addError($message, $messageType = ValidationResult::TYPE_ERROR, $code = null, $cast = ValidationResult::CAST_TEXT)
-    {
-        return $this->addFieldError(null, $message, $messageType, $code, $cast);
+    public function addError(
+        $message,
+        $messageType = ValidationResult::TYPE_ERROR,
+        $code = null,
+        $cast = ValidationResult::CAST_TEXT,
+        $value = ValidationResult::VALUE_UNSET,
+    ) {
+        return $this->addFieldError(null, $message, $messageType, $code, $cast, $value);
     }
 
     /**
@@ -89,6 +100,7 @@ class ValidationResult
      *                            This can be usedful for ensuring no duplicate messages
      * @param string|bool $cast Cast type; One of the CAST_ constant definitions.
      * Bool values will be treated as plain text flag.
+     * @param mixed $value The value that failed validation
      * @return $this
      */
     public function addFieldError(
@@ -96,10 +108,11 @@ class ValidationResult
         $message,
         $messageType = ValidationResult::TYPE_ERROR,
         $code = null,
-        $cast = ValidationResult::CAST_TEXT
+        $cast = ValidationResult::CAST_TEXT,
+        $value = ValidationResult::VALUE_UNSET,
     ) {
         $this->isValid = false;
-        return $this->addFieldMessage($fieldName, $message, $messageType, $code, $cast);
+        return $this->addFieldMessage($fieldName, $message, $messageType, $code, $cast, $value);
     }
 
     /**
@@ -112,11 +125,17 @@ class ValidationResult
      *                            This can be usedful for ensuring no duplicate messages
      * @param string|bool $cast Cast type; One of the CAST_ constant definitions.
      * Bool values will be treated as plain text flag.
+     * @param mixed $value The value that failed validation
      * @return $this
      */
-    public function addMessage($message, $messageType = ValidationResult::TYPE_ERROR, $code = null, $cast = ValidationResult::CAST_TEXT)
-    {
-        return $this->addFieldMessage(null, $message, $messageType, $code, $cast);
+    public function addMessage(
+        $message,
+        $messageType = ValidationResult::TYPE_ERROR,
+        $code = null,
+        $cast = ValidationResult::CAST_TEXT,
+        $value = ValidationResult::VALUE_UNSET,
+    ) {
+        return $this->addFieldMessage(null, $message, $messageType, $code, $cast, $value);
     }
 
     /**
@@ -130,6 +149,7 @@ class ValidationResult
      *                            This can be usedful for ensuring no duplicate messages
      * @param string|bool $cast Cast type; One of the CAST_ constant definitions.
      * Bool values will be treated as plain text flag.
+     * @param mixed $value The value that failed validation
      * @return $this
      */
     public function addFieldMessage(
@@ -137,7 +157,8 @@ class ValidationResult
         $message,
         $messageType = ValidationResult::TYPE_ERROR,
         $code = null,
-        $cast = ValidationResult::CAST_TEXT
+        $cast = ValidationResult::CAST_TEXT,
+        $value = ValidationResult::VALUE_UNSET,
     ) {
         if ($code && is_numeric($code)) {
             throw new InvalidArgumentException("Don't use a numeric code '$code'.  Use a string.");
@@ -151,7 +172,9 @@ class ValidationResult
             'messageType' => $messageType,
             'messageCast' => $cast,
         ];
-
+        if ($value !== ValidationResult::VALUE_UNSET) {
+            $metadata['value'] = $value;
+        }
         if ($code) {
             $this->messages[$code] = $metadata;
         } else {

src/Dev/SapphireTest.php

@@ -48,7 +48,7 @@ use ReflectionClass;
 use SilverStripe\Dev\Exceptions\ExpectedErrorException;
 use SilverStripe\Dev\Exceptions\ExpectedNoticeException;
 use SilverStripe\Dev\Exceptions\ExpectedWarningException;
-use SilverStripe\Dev\Exceptions\UnexpectedErrorException;
+use SilverStripe\ORM\DB;
 
 /**
  * Test case class for the Silverstripe framework.
@@ -434,6 +434,9 @@ abstract class SapphireTest extends TestCase implements TestOnly
      */
     public static function setUpBeforeClass(): void
     {
+        // Disallow the use of DB replicas in tests
+        DB::setMustUsePrimary();
+
         // Start tests
         static::start();
 

src/Forms/CompositeField.php

@@ -119,10 +119,8 @@ class CompositeField extends FormField
      * Returns the name (ID) for the element.
      * If the CompositeField doesn't have a name, but we still want the ID/name to be set.
      * This code generates the ID from the nested children.
-     *
-     * @return String $name
      */
-    public function getName()
+    public function getName(): string
     {
         if ($this->name) {
             return $this->name;

src/Forms/FieldGroup.php

@@ -106,7 +106,7 @@ class FieldGroup extends CompositeField
      * In some cases the FieldGroup doesn't have a title, but we still want
      * the ID / name to be set. This code, generates the ID from the nested children
      */
-    public function getName()
+    public function getName(): string
     {
         if ($this->name) {
             return $this->name;

src/Forms/FormField.php

@@ -15,6 +15,7 @@ use SilverStripe\Core\Validation\ValidationResult;
 use SilverStripe\View\AttributesHTML;
 use SilverStripe\View\SSViewer;
 use SilverStripe\Model\ModelData;
+use SilverStripe\Core\Validation\FieldValidation\FieldValidatorsTrait;
 
 /**
  * Represents a field in a form.
@@ -44,6 +45,7 @@ class FormField extends RequestHandler
 {
     use AttributesHTML;
     use FormMessage;
+    use FieldValidatorsTrait;
 
     /** @see $schemaDataType */
     const SCHEMA_DATA_TYPE_STRING = 'String';
@@ -424,12 +426,10 @@ class FormField extends RequestHandler
 
     /**
      * Returns the field name.
-     *
-     * @return string
      */
-    public function getName()
+    public function getName(): string
     {
-        return $this->name;
+        return $this->name ?? '';
     }
 
     /**
@@ -443,16 +443,32 @@ class FormField extends RequestHandler
     }
 
     /**
-     * Returns the field value.
+     * Alias of getValue()
      *
      * @see FormField::setSubmittedValue()
      * @return mixed
      */
     public function Value()
+    {
+        return $this->getValue();
+    }
+
+    /**
+     * Returns the field value.
+     */
+    public function getValue(): mixed
     {
         return $this->value;
     }
 
+    /**
+     * Get the value of this field for field validation
+     */
+    public function getValueForValidation(): mixed
+    {
+        return $this->getValue();
+    }
+
     /**
      * Method to save this form field into the given record.
      *
@@ -1231,15 +1247,28 @@ class FormField extends RequestHandler
     }
 
     /**
-     * Abstract method each {@link FormField} subclass must implement, determines whether the field
-     * is valid or not based on the value.
+     * Subclasses can define an existing FieldValidatorClass to validate the FormField value
+     * They may also override this method to provide custom validation logic
      *
      * @param Validator $validator
      * @return bool
      */
     public function validate($validator)
     {
-        return $this->extendValidationResult(true, $validator);
+        $isValid = true;
+        $result = ValidationResult::create();
+        $fieldValidators = $this->getFieldValidators();
+        foreach ($fieldValidators as $fieldValidator) {
+            $validationResult = $fieldValidator->validate();
+            if (!$validationResult->isValid()) {
+                $result->combineAnd($validationResult);
+            }
+        }
+        if (!$result->isValid()) {
+            $isValid = false;
+            $validator->getResult()->combineAnd($result);
+        }
+        return $this->extendValidationResult($isValid, $validator);
     }
 
     /**

src/Forms/SelectionGroup_Item.php

@@ -43,7 +43,7 @@ class SelectionGroup_Item extends CompositeField
         return $this;
     }
 
-    function getValue()
+    function getValue(): mixed
     {
         return $this->value;
     }

src/Forms/TextField.php

@@ -117,31 +117,6 @@ class TextField extends FormField implements TippableFieldInterface
         return $data;
     }
 
-    /**
-     * Validate this field
-     *
-     * @param Validator $validator
-     * @return bool
-     */
-    public function validate($validator)
-    {
-        $result = true;
-        if (!is_null($this->maxLength) && mb_strlen($this->value ?? '') > $this->maxLength) {
-            $name = strip_tags($this->Title() ? $this->Title() : $this->getName());
-            $validator->validationError(
-                $this->name,
-                _t(
-                    'SilverStripe\\Forms\\TextField.VALIDATEMAXLENGTH',
-                    'The value for {name} must not exceed {maxLength} characters in length',
-                    ['name' => $name, 'maxLength' => $this->maxLength]
-                ),
-                "validation"
-            );
-            $result = false;
-        }
-        return $this->extendValidationResult($result, $validator);
-    }
-
     public function getSchemaValidation()
     {
         $rules = parent::getSchemaValidation();

src/Forms/UrlField.php

@@ -53,12 +53,12 @@ class UrlField extends TextField
     }
 
     /**
-     * Set which protocols valid URLs are allowed to have
+     * Set which protocols valid URLs are allowed to have.
+     * Passing an empty array will result in using configured defaults.
      */
     public function setAllowedProtocols(array $protocols): static
     {
-        // Ensure the array isn't associative so we can use 0 index in validate().
-        $this->protocols = array_keys($protocols);
+        $this->protocols = $protocols;
         return $this;
     }
 
@@ -67,10 +67,12 @@ class UrlField extends TextField
      */
     public function getAllowedProtocols(): array
     {
-        if (empty($this->protocols)) {
-            return static::config()->get('default_protocols');
+        $protocols = $this->protocols;
+        if (empty($protocols)) {
+            $protocols = static::config()->get('default_protocols');
         }
-        return $this->protocols;
+        // Ensure the array isn't associative so we can use 0 index in validate().
+        return array_values($protocols);
     }
 
     /**

src/ORM/Connect/TempDatabase.php

@@ -43,7 +43,7 @@ class TempDatabase
      *
      * @param string $name DB Connection name to use
      */
-    public function __construct($name = 'default')
+    public function __construct($name = DB::CONN_PRIMARY)
     {
         $this->name = $name;
     }

src/ORM/DB.php

@@ -3,6 +3,7 @@
 namespace SilverStripe\ORM;
 
 use InvalidArgumentException;
+use RunTimeException;
 use SilverStripe\Control\Director;
 use SilverStripe\Control\HTTPRequest;
 use SilverStripe\Core\Config\Config;
@@ -21,6 +22,22 @@ use SilverStripe\ORM\Queries\SQLExpression;
  */
 class DB
 {
+    /**
+     * A dynamic connection that will use either a replica connection (if one is
+     * available and not forced to use the 'primary' connection), or the 'primary' connection
+     */
+    public const CONN_DYNAMIC = 'dynamic';
+
+    /**
+     * The 'primary' connection name, which is the main database connection and is used for all write
+     * operations and for read operations when the 'dynamic' connection is forced to use the 'primary' connection
+     */
+    public const CONN_PRIMARY = 'primary';
+
+    /**
+     * The maximum number of replicas databases that can be configured
+     */
+    public const MAX_REPLICAS = 99;
 
     /**
      * This constant was added in SilverStripe 2.4 to indicate that SQL-queries
@@ -58,19 +75,47 @@ class DB
      */
     protected static $configs = [];
 
-
-
     /**
      * The last SQL query run.
      * @var string
      */
     public static $lastQuery;
 
+    /**
+     * The name of the last connection used. This is only used for unit-testing purposes.
+     * @interal
+     */
+    private static string $lastConnectionName = '';
+
     /**
      * Internal flag to keep track of when db connection was attempted.
+     *
+     * @internal
      */
     private static $connection_attempted = false;
 
+    /**
+     * Only use the primary database connection for the rest of the current request
+     *
+     * @internal
+     */
+    private static bool $mustUsePrimary = false;
+
+    /**
+     * Used by DB::withPrimary() to count the number of times it has been called
+     * Uses an int instead of a bool to allow for nested calls
+     *
+     * @internal
+     */
+    private static int $withPrimaryCount = 0;
+
+    /**
+     * The key of the replica config to use for this request
+     *
+     * @internal
+     */
+    private static string $replicaConfigKey = '';
+
     /**
      * Set the global database connection.
      * Pass an object that's a subclass of SS_Database.  This object will be used when {@link DB::query()}
@@ -78,11 +123,11 @@ class DB
      *
      * @param Database $connection The connection object to set as the connection.
      * @param string $name The name to give to this connection.  If you omit this argument, the connection
-     * will be the default one used by the ORM.  However, you can store other named connections to
+     * will be the primary one used by the ORM.  However, you can store other named connections to
      * be accessed through DB::get_conn($name).  This is useful when you have an application that
      * needs to connect to more than one database.
      */
-    public static function set_conn(Database $connection, $name = 'default')
+    public static function set_conn(Database $connection, $name)
     {
         DB::$connections[$name] = $connection;
     }
@@ -92,11 +137,17 @@ class DB
      *
      * @param string $name An optional name given to a connection in the DB::setConn() call.  If omitted,
      * the default connection is returned.
-     * @return Database
+     * @return Database|null
      */
-    public static function get_conn($name = 'default')
+    public static function get_conn($name = DB::CONN_DYNAMIC)
     {
+        // Allow default to connect to replica if configured
+        if ($name === DB::CONN_DYNAMIC) {
+            $name = DB::getDynamicConnectionName();
+        }
+
         if (isset(DB::$connections[$name])) {
+            DB::$lastConnectionName = $name;
             return DB::$connections[$name];
         }
 
@@ -109,14 +160,50 @@ class DB
         return null;
     }
 
+    /**
+     * Whether the primary database connection will be used if the database is used right now
+     */
+    public static function willUsePrimary(): bool
+    {
+        return DB::$mustUsePrimary || DB::$withPrimaryCount > 0 || !DB::hasReplicaConfig();
+    }
+
+    /**
+     * Set to use the primary database connection for rest of the current request
+     * meaning that replia connections will no longer be used
+     *
+     * This intentioally does not have a parameter to set this back to false, as this it to prevent
+     * accidentally attempting writing to a replica, or reading from an out of date replica
+     * after a write
+     */
+    public static function setMustUsePrimary(): void
+    {
+        DB::$mustUsePrimary = true;
+    }
+
+    /**
+     * Only use the primary database connection when calling $callback
+     * Use this when doing non-mutable queries on the primary database where querying
+     * an out of sync replica could cause issues
+     * There's no need to use this with mutable queries, or after calling a mutable query
+     * as the primary database connection will be automatically used
+     */
+    public static function withPrimary(callable $callback): mixed
+    {
+        DB::$withPrimaryCount++;
+        $result = $callback();
+        DB::$withPrimaryCount--;
+        return $result;
+    }
+
     /**
      * Retrieves the schema manager for the current database
      *
-     * @param string $name An optional name given to a connection in the DB::setConn() call.  If omitted,
-     * the default connection is returned.
-     * @return DBSchemaManager
+     * @param string $name An optional name given to a connection in the DB::setConn() call.
+     * If omitted, a dynamic connection is returned.
+     * @return DBSchemaManager|null
      */
-    public static function get_schema($name = 'default')
+    public static function get_schema($name = DB::CONN_DYNAMIC)
     {
         $connection = DB::get_conn($name);
         if ($connection) {
@@ -130,11 +217,11 @@ class DB
      *
      * @param SQLExpression $expression The expression object to build from
      * @param array $parameters Out parameter for the resulting query parameters
-     * @param string $name An optional name given to a connection in the DB::setConn() call.  If omitted,
-     * the default connection is returned.
-     * @return string The resulting SQL as a string
+     * @param string $name An optional name given to a connection in the DB::setConn() call.
+     * If omitted, a dynamic connection is returned.
+     * @return string|null The resulting SQL as a string
      */
-    public static function build_sql(SQLExpression $expression, &$parameters, $name = 'default')
+    public static function build_sql(SQLExpression $expression, &$parameters, $name = DB::CONN_DYNAMIC)
     {
         $connection = DB::get_conn($name);
         if ($connection) {
@@ -148,11 +235,11 @@ class DB
     /**
      * Retrieves the connector object for the current database
      *
-     * @param string $name An optional name given to a connection in the DB::setConn() call.  If omitted,
-     * the default connection is returned.
-     * @return DBConnector
+     * @param string $name An optional name given to a connection in the DB::setConn() call.
+     * If omitted, a dynamic connection is returned.
+     * @return DBConnector|null
      */
-    public static function get_connector($name = 'default')
+    public static function get_connector($name = DB::CONN_DYNAMIC)
     {
         $connection = DB::get_conn($name);
         if ($connection) {
@@ -268,8 +355,13 @@ class DB
      * @param string $label identifier for the connection
      * @return Database
      */
-    public static function connect($databaseConfig, $label = 'default')
+    public static function connect($databaseConfig, $label = DB::CONN_DYNAMIC)
     {
+        // Allow default to connect to replica if configured
+        if ($label === DB::CONN_DYNAMIC) {
+            $label = DB::getDynamicConnectionName();
+        }
+
         // This is used by the "testsession" module to test up a test session using an alternative name
         if ($name = DB::get_alternative_database_name()) {
             $databaseConfig['database'] = $name;
@@ -288,6 +380,7 @@ class DB
         $conn = Injector::inst()->create($dbClass);
         DB::set_conn($conn, $label);
         $conn->connect($databaseConfig);
+        DB::$lastConnectionName = $label;
 
         return $conn;
     }
@@ -298,7 +391,7 @@ class DB
      * @param array $databaseConfig
      * @param string $name
      */
-    public static function setConfig($databaseConfig, $name = 'default')
+    public static function setConfig($databaseConfig, $name = DB::CONN_PRIMARY)
     {
         static::$configs[$name] = $databaseConfig;
     }
@@ -309,13 +402,42 @@ class DB
      * @param string $name
      * @return mixed
      */
-    public static function getConfig($name = 'default')
+    public static function getConfig($name = DB::CONN_PRIMARY)
     {
-        if (isset(static::$configs[$name])) {
+        if (static::hasConfig($name)) {
             return static::$configs[$name];
         }
     }
 
+    /**
+     * Check if a named connection config exists
+     */
+    public static function hasConfig($name = DB::CONN_PRIMARY): bool
+    {
+        return array_key_exists($name, static::$configs);
+    }
+
+    /**
+     * Get a replica database configuration key
+     * e.g. replica_01
+     */
+    public static function getReplicaConfigKey(int $replica): string
+    {
+        $len = strlen((string) DB::MAX_REPLICAS);
+        return 'replica_' . str_pad($replica, $len, '0', STR_PAD_LEFT);
+    }
+
+    /**
+     * Check if there are any replica configurations
+     */
+    public static function hasReplicaConfig(): bool
+    {
+        $configKeys = array_keys(static::$configs);
+        return !empty(array_filter($configKeys, function (string $key) {
+            return (bool) preg_match('#^replica_[0-9]+$#', $key);
+        }));
+    }
+
     /**
      * Returns true if a database connection has been attempted.
      * In particular, it lets the caller know if we're still so early in the execution pipeline that
@@ -335,8 +457,8 @@ class DB
     public static function query($sql, $errorLevel = E_USER_ERROR)
     {
         DB::$lastQuery = $sql;
-
-        return DB::get_conn()->query($sql, $errorLevel);
+        $name = DB::getDynamicConnectionName($sql);
+        return DB::get_conn($name)->query($sql, $errorLevel);
     }
 
     /**
@@ -427,8 +549,8 @@ class DB
     public static function prepared_query($sql, $parameters, $errorLevel = E_USER_ERROR)
     {
         DB::$lastQuery = $sql;
-
-        return DB::get_conn()->preparedQuery($sql, $parameters, $errorLevel);
+        $name = DB::getDynamicConnectionName($sql);
+        return DB::get_conn($name)->preparedQuery($sql, $parameters, $errorLevel);
     }
 
     /**
@@ -680,4 +802,63 @@ class DB
     {
         DB::get_schema()->alterationMessage($message, $type);
     }
+
+    /**
+     * Get the name of the database connection to use for the given SQL query
+     * The 'dynamic' connection can be either the primary or a replica connection if configured
+     */
+    private static function getDynamicConnectionName(string $sql = ''): string
+    {
+        if (DB::willUsePrimary()) {
+            return DB::CONN_PRIMARY;
+        }
+        if (DB::isMutableSql($sql)) {
+            DB::$mustUsePrimary = true;
+            return DB::CONN_PRIMARY;
+        }
+        if (DB::$replicaConfigKey) {
+            return DB::$replicaConfigKey;
+        }
+        $name = DB::getRandomReplicaConfigKey();
+        DB::$replicaConfigKey = $name;
+        return $name;
+    }
+
+    /**
+     * Check if the given SQL query is mutable
+     */
+    private static function isMutableSql(string $sql): bool
+    {
+        $dbClass = DB::getConfig(DB::CONN_PRIMARY)['type'];
+        // This must use getServiceSpec() and not Injector::get/create() followed by
+        // getConnector() as this can remove the dbConn from a different connection
+        // under edge case conditions
+        $dbSpec = Injector::inst()->getServiceSpec($dbClass);
+        $connectorService = $dbSpec['properties']['connector'];
+        $connector = Injector::inst()->convertServiceProperty($connectorService);
+        return $connector->isQueryMutable($sql);
+    }
+
+    /**
+     * Get a random replica database configuration key from the available replica configurations
+     * The replica choosen will be used for the rest of the request, unless the primary connection
+     * is forced
+     */
+    private static function getRandomReplicaConfigKey(): string
+    {
+        $replicaNumbers = [];
+        for ($i = 1; $i <= DB::MAX_REPLICAS; $i++) {
+            $replicaKey = DB::getReplicaConfigKey($i);
+            if (!DB::hasConfig($replicaKey)) {
+                break;
+            }
+            $replicaNumbers[] = $i;
+        }
+        if (count($replicaNumbers) === 0) {
+            throw new RunTimeException('No replica configurations found');
+        }
+        // Choose a random replica
+        $index = rand(0, count($replicaNumbers) - 1);
+        return DB::getReplicaConfigKey($replicaNumbers[$index]);
+    }
 }

src/ORM/DataList.php

@@ -237,7 +237,7 @@ class DataList extends ModelData implements SS_List, Filterable, Sortable, Limit
      */
     public function sql(&$parameters = [])
     {
-        return $this->dataQuery->query()->sql($parameters);
+        return $this->dataQuery->sql($parameters);
     }
 
     /**
@@ -1040,7 +1040,7 @@ class DataList extends ModelData implements SS_List, Filterable, Sortable, Limit
 
     private function executeQuery(): Query
     {
-        $query = $this->dataQuery->query()->execute();
+        $query = $this->dataQuery->execute();
         $this->fetchEagerLoadRelations($query);
         return $query;
     }

src/ORM/DataObject.php

@@ -145,6 +145,14 @@ class DataObject extends ModelData implements DataObjectInterface, i18nEntityPro
      */
     private static $default_classname = null;
 
+    /**
+     * Whether this DataObject class must only use the primary database and not a read-only replica
+     * Note that this will be only be enforced when using DataQuery::execute() or
+     * another method that uses calls DataQuery::execute() internally e.g. DataObject::get()
+     * This will not be enforced when using low-level ORM functionality to query data e.g. SQLSelect or DB::query()
+     */
+    private static bool $must_use_primary_db = false;
+
     /**
      * Data stored in this objects database record. An array indexed by fieldname.
      *
@@ -1230,6 +1238,15 @@ class DataObject extends ModelData implements DataObjectInterface, i18nEntityPro
     public function validate()
     {
         $result = ValidationResult::create();
+        // Call DBField::validate() on every DBField
+        $specs = static::getSchema()->fieldSpecs(static::class);
+        foreach (array_keys($specs) as $fieldName) {
+            $dbField = $this->dbObject($fieldName);
+            $validationResult = $dbField->validate();
+            if (!$validationResult->isValid()) {
+                $result->combineAnd($validationResult);
+            }
+        }
         $this->extend('updateValidate', $result);
         return $result;
     }
@@ -3268,6 +3285,9 @@ class DataObject extends ModelData implements DataObjectInterface, i18nEntityPro
         /** @var DBField $obj */
         $table = $schema->tableName($class);
         $obj = Injector::inst()->create($spec, $fieldName);
+        if (is_null($value)) {
+            $value = $obj->getDefaultValue();
+        }
         $obj->setTable($table);
         $obj->setValue($value, $this, false);
         return $obj;

src/ORM/DataQuery.php

@@ -10,6 +10,7 @@ use SilverStripe\ORM\Connect\Query;
 use SilverStripe\ORM\Queries\SQLConditionGroup;
 use SilverStripe\ORM\Queries\SQLSelect;
 use InvalidArgumentException;
+use SilverStripe\Core\Config\Config;
 
 /**
  * An object representing a query of data from the DataObject's supporting database.
@@ -449,7 +450,9 @@ class DataQuery
      */
     public function execute()
     {
-        return $this->getFinalisedQuery()->execute();
+        return $this->withCorrectDatabase(
+            fn() => $this->getFinalisedQuery()->execute()
+        );
     }
 
     /**
@@ -472,7 +475,9 @@ class DataQuery
     public function count()
     {
         $quotedColumn = DataObject::getSchema()->sqlColumnForField($this->dataClass(), 'ID');
-        return $this->getFinalisedQuery()->count("DISTINCT {$quotedColumn}");
+        return $this->withCorrectDatabase(
+            fn() => $this->getFinalisedQuery()->count("DISTINCT {$quotedColumn}")
+        );
     }
 
     /**
@@ -501,7 +506,9 @@ class DataQuery
 
         // Wrap the whole thing in an "EXISTS"
         $sql = 'SELECT CASE WHEN EXISTS(' . $statement->sql($params) . ') THEN 1 ELSE 0 END';
-        $result = DB::prepared_query($sql, $params);
+        $result = $this->withCorrectDatabase(
+            fn() => DB::prepared_query($sql, $params)
+        );
         $row = $result->record();
         $result = reset($row);
 
@@ -582,7 +589,9 @@ class DataQuery
      */
     public function aggregate($expression)
     {
-        return $this->getFinalisedQuery()->aggregate($expression)->execute()->value();
+        return $this->withCorrectDatabase(
+            fn() => $this->getFinalisedQuery()->aggregate($expression)->execute()->value()
+        );
     }
 
     /**
@@ -593,7 +602,9 @@ class DataQuery
      */
     public function firstRow()
     {
-        return $this->getFinalisedQuery()->firstRow();
+        return $this->withCorrectDatabase(
+            fn() => $this->getFinalisedQuery()->firstRow()
+        );
     }
 
     /**
@@ -604,7 +615,9 @@ class DataQuery
      */
     public function lastRow()
     {
-        return $this->getFinalisedQuery()->lastRow();
+        return $this->withCorrectDatabase(
+            fn() => $this->getFinalisedQuery()->lastRow()
+        );
     }
 
     /**
@@ -1344,7 +1357,9 @@ class DataQuery
         $query->selectField($fieldExpression, $field);
         $this->ensureSelectContainsOrderbyColumns($query, $originalSelect);
 
-        return $query->execute()->column($field);
+        return $this->withCorrectDatabase(
+            fn() => $query->execute()->column($field)
+        );
     }
 
     /**
@@ -1495,4 +1510,16 @@ class DataQuery
 
         return $updated;
     }
+
+    /**
+     * Calls a callback on either the primary database or a replica, with respect to the configured
+     * value of `must_use_primary_db` on the current dataClass
+     */
+    private function withCorrectDatabase(callable $callback): mixed
+    {
+        if (Config::inst()->get($this->dataClass(), 'must_use_primary_db')) {
+            return DB::withPrimary($callback);
+        }
+        return $callback();
+    }
 }

src/ORM/FieldType/DBBigInt.php

@@ -2,18 +2,24 @@
 
 namespace SilverStripe\ORM\FieldType;
 
+use SilverStripe\Core\Validation\FieldValidation\IntFieldValidator;
+use SilverStripe\Core\Validation\FieldValidation\BigIntFieldValidator;
 use SilverStripe\ORM\DB;
 
 /**
  * Represents a signed 8 byte integer field. Do note PHP running as 32-bit might not work with Bigint properly, as it
  * would convert the value to a float when queried from the database since the value is a 64-bit one.
  *
- * @package framework
- * @subpackage model
- * @see Int
+ * BigInt is always signed i.e. can be negative
+ * Their range is -9223372036854775808 to 9223372036854775807
  */
 class DBBigInt extends DBInt
 {
+    private static array $field_validators = [
+        // Remove parent validator and add BigIntValidator instead
+        IntFieldValidator::class => null,
+        BigIntFieldValidator::class,
+    ];
 
     public function requireField(): void
     {
@@ -24,7 +30,6 @@ class DBBigInt extends DBInt
             'default' => $this->defaultVal,
             'arrayValue' => $this->arrayValue
         ];
-
         $values = ['type' => 'bigint', 'parts' => $parts];
         DB::require_field($this->tableName, $this->name, $values);
     }

src/ORM/FieldType/DBBoolean.php

@@ -2,6 +2,7 @@
 
 namespace SilverStripe\ORM\FieldType;
 
+use SilverStripe\Core\Validation\FieldValidation\BooleanFieldValidator;
 use SilverStripe\Forms\CheckboxField;
 use SilverStripe\Forms\DropdownField;
 use SilverStripe\Forms\FormField;
@@ -9,13 +10,18 @@ use SilverStripe\ORM\DB;
 use SilverStripe\Model\ModelData;
 
 /**
- * Represents a boolean field.
+ * Represents a boolean field
+ * Values are stored in the database as tinyint i.e. 1 or 0
  */
 class DBBoolean extends DBField
 {
-    public function __construct(?string $name = null, bool|int $defaultVal = 0)
+    private static array $field_validators = [
+        BooleanFieldValidator::class,
+    ];
+
+    public function __construct(?string $name = null, bool $defaultVal = false)
     {
-        $this->defaultVal = ($defaultVal) ? 1 : 0;
+        $this->setDefaultValue($defaultVal);
 
         parent::__construct($name);
     }
@@ -34,6 +40,13 @@ class DBBoolean extends DBField
         DB::require_field($this->tableName, $this->name, $values);
     }
 
+    public function setValue(mixed $value, null|array|ModelData $record = null, bool $markChanged = true): static
+    {
+        parent::setValue($value);
+        $this->value = $this->convertBooleanLikeValue($value);
+        return $this;
+    }
+
     public function Nice(): string
     {
         return ($this->value) ? _t(__CLASS__ . '.YESANSWER', 'Yes') : _t(__CLASS__ . '.NOANSWER', 'No');
@@ -51,7 +64,7 @@ class DBBoolean extends DBField
             if ($this->value instanceof DBField) {
                 $this->value->saveInto($dataObject);
             } else {
-                $dataObject->__set($fieldName, $this->value ? 1 : 0);
+                $dataObject->__set($fieldName, $this->value ? true : false);
             }
         } else {
             $class = static::class;
@@ -69,37 +82,50 @@ class DBBoolean extends DBField
         $anyText = _t(__CLASS__ . '.ANY', 'Any');
         $source = [
             '' => $anyText,
-            1 => _t(__CLASS__ . '.YESANSWER', 'Yes'),
-            0 => _t(__CLASS__ . '.NOANSWER', 'No')
+            '1' => _t(__CLASS__ . '.YESANSWER', 'Yes'),
+            '0' => _t(__CLASS__ . '.NOANSWER', 'No')
         ];
 
         return DropdownField::create($this->name, $title, $source)
             ->setEmptyString($anyText);
     }
 
-    public function nullValue(): ?int
+    public function nullValue(): int
     {
         return 0;
     }
 
     public function prepValueForDB(mixed $value): array|int|null
     {
-        if (is_bool($value)) {
-            return $value ? 1 : 0;
-        }
-        if (empty($value)) {
-            return 0;
+        $bool = $this->convertBooleanLikeValue($value);
+        // Ensure a tiny int is returned no matter what e.g. value is an
+        return $bool ? 1 : 0;
     }
+
+    /**
+     * Convert boolean-like values to boolean
+     * Does not convert non-boolean-like values e.g. array - will be handled by the FieldValidator
+     */
+    private function convertBooleanLikeValue(mixed $value): mixed
+    {
         if (is_string($value)) {
-            switch (strtolower($value ?? '')) {
+            switch (strtolower($value)) {
                 case 'false':
                 case 'f':
-                    return 0;
+                case '0':
+                    return false;
                 case 'true':
                 case 't':
-                    return 1;
+                case '1':
+                    return true;
             }
         }
-        return $value ? 1 : 0;
+        if ($value === 0) {
+            return false;
+        }
+        if ($value === 1) {
+            return true;
+        }
+        return $value;
     }
 }

src/ORM/FieldType/DBClassNameVarchar.php

@@ -3,6 +3,7 @@
 namespace SilverStripe\ORM\FieldType;
 
 use SilverStripe\ORM\FieldType\DBVarchar;
+use SilverStripe\Core\Validation\FieldValidation\EnumFieldValidator;
 
 /**
  * An alternative to DBClassName that stores the class name as a varchar instead of an enum
@@ -24,4 +25,8 @@ use SilverStripe\ORM\FieldType\DBVarchar;
 class DBClassNameVarchar extends DBVarchar
 {
     use DBClassNameTrait;
+
+    private static array $field_validators = [
+        EnumFieldValidator::class => ['getEnum'],
+    ];
 }

src/ORM/FieldType/DBComposite.php

@@ -8,6 +8,7 @@ use SilverStripe\ORM\DataObject;
 use SilverStripe\ORM\DB;
 use SilverStripe\ORM\Queries\SQLSelect;
 use SilverStripe\Model\ModelData;
+use SilverStripe\Core\Validation\FieldValidation\CompositeFieldValidator;
 
 /**
  * Extend this class when designing a {@link DBField} that doesn't have a 1-1 mapping with a database field.
@@ -25,6 +26,10 @@ use SilverStripe\Model\ModelData;
  */
 abstract class DBComposite extends DBField
 {
+    private static array $field_validators = [
+        CompositeFieldValidator::class,
+    ];
+
     /**
      * Similar to {@link DataObject::$db},
      * holds an array of composite field names.
@@ -190,6 +195,15 @@ abstract class DBComposite extends DBField
         return $this;
     }
 
+    public function getValueForValidation(): mixed
+    {
+        $fields = [];
+        foreach (array_keys($this->compositeDatabaseFields()) as $fieldName) {
+            $fields[] = $this->dbObject($fieldName);
+        }
+        return $fields;
+    }
+
     /**
      * Bind this field to the model, and set the underlying table to that of the owner
      */

src/ORM/FieldType/DBDate.php

@@ -12,6 +12,7 @@ use SilverStripe\ORM\DB;
 use SilverStripe\Security\Member;
 use SilverStripe\Security\Security;
 use SilverStripe\Model\ModelData;
+use SilverStripe\Core\Validation\FieldValidation\DateFieldValidator;
 
 /**
  * Represents a date field.
@@ -33,6 +34,7 @@ class DBDate extends DBField
 {
     /**
      * Standard ISO format string for date in CLDR standard format
+     * This is equivalent to php date format "Y-m-d" e.g. 2024-08-31
      */
     public const ISO_DATE = 'y-MM-dd';
 
@@ -42,13 +44,14 @@ class DBDate extends DBField
      */
     public const ISO_LOCALE = 'en_US';
 
+    private static array $field_validators = [
+        DateFieldValidator::class,
+    ];
+
     public function setValue(mixed $value, null|array|ModelData $record = null, bool $markChanged = true): static
     {
+        if ($value !== null) {
             $value = $this->parseDate($value);
-        if ($value === false) {
-            throw new InvalidArgumentException(
-                "Invalid date: '$value'. Use " . DBDate::ISO_DATE . " to prevent this error."
-            );
         }
         $this->value = $value;
         return $this;
@@ -58,15 +61,10 @@ class DBDate extends DBField
      * Parse timestamp or iso8601-ish date into standard iso8601 format
      *
      * @param mixed $value
-     * @return string|null|false Formatted date, null if empty but valid, or false if invalid
+     * @return mixed Formatted date, or the original value if it couldn't be parsed
      */
-    protected function parseDate(mixed $value): string|null|false
+    protected function parseDate(mixed $value): mixed
     {
-        // Skip empty values
-        if (empty($value) && !is_numeric($value)) {
-            return null;
-        }
-
         // Determine value to parse
         if (is_array($value)) {
             $source = $value; // parse array
@@ -74,19 +72,23 @@ class DBDate extends DBField
             $source = $value; // parse timestamp
         } else {
             // Convert US date -> iso, fix y2k, etc
-            $value = $this->fixInputDate($value);
-            if (is_null($value)) {
-                return null;
+            $fixedValue = $this->fixInputDate($value);
+            if ($fixedValue === '') {
+                // Dates with an invalid format will be caught by validator later
+                return $value;
             }
-            $source = strtotime($value ?? ''); // convert string to timestamp
+            // convert string to timestamp
+            $source = strtotime($fixedValue ?? '');
         }
-        if ($value === false) {
-            return false;
+        if (!$source && $source !== 0 and $source !== '0') {
+            // Unable to parse date, keep as is so that the validator can catch it later
+            // Note that 0 and '0' are valid dates for Jan 1 1970
+            return $value;
         }
-
         // Format as iso8601
         $formatter = $this->getInternalFormatter();
-        return $formatter->format($source);
+        $ret = $formatter->format($source);
+        return $ret;
     }
 
     /**
@@ -554,26 +556,14 @@ class DBDate extends DBField
 
     /**
      * Fix non-iso dates
-     *
-     * @param string $value
-     * @return string
      */
-    protected function fixInputDate($value)
+    protected function fixInputDate(string $value): string
     {
-        // split
         [$year, $month, $day, $time] = $this->explodeDateString($value);
-
-        if ((int)$year === 0 && (int)$month === 0 && (int)$day === 0) {
-            return null;
+        if (!checkdate((int) $month, (int) $day, (int) $year)) {
+            return '';
         }
-        // Validate date
-        if (!checkdate($month ?? 0, $day ?? 0, $year ?? 0)) {
-            throw new InvalidArgumentException(
-                "Invalid date: '$value'. Use " . DBDate::ISO_DATE . " to prevent this error."
-            );
-        }
-
-        // Convert to y-m-d
+        // Convert to Y-m-d
         return sprintf('%d-%02d-%02d%s', $year, $month, $day, $time);
     }
 
@@ -591,11 +581,8 @@ class DBDate extends DBField
             $value ?? '',
             $matches
         )) {
-            throw new InvalidArgumentException(
-                "Invalid date: '$value'. Use " . DBDate::ISO_DATE . " to prevent this error."
-            );
+            return [0, 0, 0, ''];
         }
-
         $parts = [
             $matches['first'],
             $matches['second'],
@@ -605,11 +592,6 @@ class DBDate extends DBField
         if ($parts[0] < 1000 && $parts[2] > 1000) {
             $parts = array_reverse($parts ?? []);
         }
-        if ($parts[0] < 1000 && (int)$parts[0] !== 0) {
-            throw new InvalidArgumentException(
-                "Invalid date: '$value'. Use " . DBDate::ISO_DATE . " to prevent this error."
-            );
-        }
         $parts[] = $matches['time'];
         return $parts;
     }

src/ORM/FieldType/DBDatetime.php

@@ -13,6 +13,8 @@ use SilverStripe\Security\Member;
 use SilverStripe\Security\Security;
 use SilverStripe\View\TemplateGlobalProvider;
 use SilverStripe\Model\ModelData;
+use SilverStripe\Core\Validation\FieldValidation\DatetimeFieldValidator;
+use SilverStripe\Core\Validation\FieldValidation\DateFieldValidator;
 
 /**
  * Represents a date-time field.
@@ -39,6 +41,7 @@ class DBDatetime extends DBDate implements TemplateGlobalProvider
     /**
      * Standard ISO format string for date and time in CLDR standard format,
      * with a whitespace separating date and time (common database representation, e.g. in MySQL).
+     * This is equivalent to php date format "Y-m-d H:i:s" e.g. 2024-08-31 09:30:00
      */
     public const ISO_DATETIME = 'y-MM-dd HH:mm:ss';
 
@@ -48,10 +51,16 @@ class DBDatetime extends DBDate implements TemplateGlobalProvider
      */
     public const ISO_DATETIME_NORMALISED = 'y-MM-dd\'T\'HH:mm:ss';
 
+    private static array $field_validators = [
+        DatetimeFieldValidator::class,
+        // disable parent validator
+        DateFieldValidator::class => null,
+    ];
+
     /**
      * Flag idicating if this field is considered immutable
      * when this is enabled setting the value of this field will return a new field instance
-     * instead updatin the old one
+     * instead updating the old one
      */
     protected bool $immutable = false;
 

src/ORM/FieldType/DBDecimal.php

@@ -2,6 +2,7 @@
 
 namespace SilverStripe\ORM\FieldType;
 
+use SilverStripe\Core\Validation\FieldValidation\DecimalFieldValidator;
 use SilverStripe\Forms\FormField;
 use SilverStripe\Forms\NumericField;
 use SilverStripe\ORM\DB;
@@ -12,6 +13,10 @@ use SilverStripe\Model\ModelData;
  */
 class DBDecimal extends DBField
 {
+    private static array $field_validators = [
+        DecimalFieldValidator::class => ['getWholeSize', 'getDecimalSize'],
+    ];
+
     /**
      * Whole number size
      */
@@ -35,7 +40,7 @@ class DBDecimal extends DBField
         $this->wholeSize = is_int($wholeSize) ? $wholeSize : 9;
         $this->decimalSize = is_int($decimalSize) ? $decimalSize : 2;
 
-        $this->defaultValue = number_format((float) $defaultValue, $this->decimalSize);
+        $this->setDefaultValue(round($defaultValue, $this->decimalSize));
 
         parent::__construct($name);
     }
@@ -50,6 +55,16 @@ class DBDecimal extends DBField
         return floor($this->value ?? 0.0);
     }
 
+    public function getWholeSize(): int
+    {
+        return $this->wholeSize;
+    }
+
+    public function getDecimalSize(): int
+    {
+        return $this->decimalSize;
+    }
+
     public function requireField(): void
     {
         $parts = [
@@ -67,6 +82,16 @@ class DBDecimal extends DBField
         DB::require_field($this->tableName, $this->name, $values);
     }
 
+    public function setValue(mixed $value, null|array|ModelData $record = null, bool $markChanged = true): static
+    {
+        parent::setValue($value, $record, $markChanged);
+        // Cast ints and numeric strings to floats
+        if (is_int($this->value) || (is_string($this->value) && is_numeric($this->value))) {
+            $this->value = (float) $value;
+        }
+        return $this;
+    }
+
     public function saveInto(ModelData $model): void
     {
         $fieldName = $this->name;
@@ -91,7 +116,7 @@ class DBDecimal extends DBField
             ->setScale($this->decimalSize);
     }
 
-    public function nullValue(): ?int
+    public function nullValue(): int
     {
         return 0;
     }

src/ORM/FieldType/DBEmail.php

@@ -0,0 +1,29 @@
+<?php
+
+namespace SilverStripe\ORM\FieldType;
+
+use SilverStripe\Forms\EmailField;
+use SilverStripe\ORM\FieldType\DBVarchar;
+use SilverStripe\Core\Validation\FieldValidation\EmailFieldValidator;
+use SilverStripe\Forms\FormField;
+use SilverStripe\Forms\NullableField;
+
+class DBEmail extends DBVarchar
+{
+    private static array $field_validators = [
+        EmailFieldValidator::class,
+    ];
+
+    public function scaffoldFormField(?string $title = null, array $params = []): ?FormField
+    {
+        // Set field with appropriate size
+        $field = EmailField::create($this->name, $title);
+        $field->setMaxLength($this->getSize());
+
+        // Allow the user to select if it's null instead of automatically assuming empty string is
+        if (!$this->getNullifyEmpty()) {
+            return NullableField::create($field);
+        }
+        return $field;
+    }
+}

src/ORM/FieldType/DBEnum.php

@@ -3,12 +3,14 @@
 namespace SilverStripe\ORM\FieldType;
 
 use SilverStripe\Core\Config\Config;
+use SilverStripe\Core\Validation\FieldValidation\EnumFieldValidator;
 use SilverStripe\Forms\DropdownField;
 use SilverStripe\Forms\FormField;
 use SilverStripe\Forms\SelectField;
 use SilverStripe\Core\ArrayLib;
 use SilverStripe\ORM\Connect\MySQLDatabase;
 use SilverStripe\ORM\DB;
+use SilverStripe\Model\ModelData;
 
 /**
  * Class Enum represents an enumeration of a set of strings.
@@ -17,6 +19,10 @@ use SilverStripe\ORM\DB;
  */
 class DBEnum extends DBString
 {
+    private static array $field_validators = [
+        EnumFieldValidator::class => ['getEnum'],
+    ];
+
     /**
      * List of enum values
      */
@@ -73,14 +79,14 @@ class DBEnum extends DBString
 
             // If there's a default, then use this
             if ($default && !is_int($default)) {
-                if (in_array($default, $enum ?? [])) {
+                if (in_array($default, $enum)) {
                     $this->setDefault($default);
                 } else {
                     throw new \InvalidArgumentException(
                         "Enum::__construct() The default value '$default' does not match any item in the enumeration"
                     );
                 }
-            } elseif (is_int($default) && $default < count($enum ?? [])) {
+            } elseif (is_int($default) && $default < count($enum)) {
                 // Set to specified index if given
                 $this->setDefault($enum[$default]);
             } else {
@@ -170,6 +176,11 @@ class DBEnum extends DBString
         return $this->enum;
     }
 
+    public function nullValue(): string
+    {
+        return '';
+    }
+
     /**
      * Get the list of enum values, including obsolete values still present in the database
      *

src/ORM/FieldType/DBField.php

@@ -10,6 +10,8 @@ use SilverStripe\Forms\TextField;
 use SilverStripe\ORM\Filters\SearchFilter;
 use SilverStripe\ORM\Queries\SQLSelect;
 use SilverStripe\Model\ModelData;
+use SilverStripe\Core\Validation\FieldValidation\FieldValidatorsTrait;
+use SilverStripe\Core\Validation\FieldValidation\FieldValidationInterface;
 
 /**
  * Single field in the database.
@@ -41,8 +43,9 @@ use SilverStripe\Model\ModelData;
  * }
  * </code>
  */
-abstract class DBField extends ModelData implements DBIndexable
+abstract class DBField extends ModelData implements DBIndexable, FieldValidationInterface
 {
+    use FieldValidatorsTrait;
 
     /**
      * Raw value of this field
@@ -99,12 +102,14 @@ abstract class DBField extends ModelData implements DBIndexable
         'ProcessedRAW' => 'HTMLFragment',
     ];
 
+    private static array $field_validators = [];
+
     /**
      * Default value in the database.
      * Might be overridden on DataObject-level, but still useful for setting defaults on
      * already existing records after a db-build.
      */
-    protected mixed $defaultVal = null;
+    private mixed $defaultValue = null;
 
     /**
      * Provide the DBField name and an array of options, e.g. ['index' => true], or ['nullifyEmpty' => false]
@@ -121,6 +126,8 @@ abstract class DBField extends ModelData implements DBIndexable
             }
             $this->setOptions($options);
         }
+        // Setting value needs to happen below the call to setOptions() in case the default value is set there
+        $this->value = $this->getDefaultValue();
 
         parent::__construct();
     }
@@ -161,7 +168,7 @@ abstract class DBField extends ModelData implements DBIndexable
      *
      * If you try an alter the name a warning will be thrown.
      */
-    public function setName(?string $name): static
+    public function setName(string $name): static
     {
         if ($this->name && $this->name !== $name) {
             user_error("DBField::setName() shouldn't be called once a DBField already has a name."
@@ -189,6 +196,18 @@ abstract class DBField extends ModelData implements DBIndexable
         return $this->value;
     }
 
+    /**
+     * Get the value of this field for field validation
+     */
+    public function getValueForValidation(): mixed
+    {
+        $value = $this->getValue();
+        if (is_null($value)) {
+            return $this->nullValue();
+        }
+        return $value;
+    }
+
     /**
      * Set the value of this field in various formats.
      * Used by {@link DataObject->getField()}, {@link DataObject->setCastedField()}
@@ -214,7 +233,7 @@ abstract class DBField extends ModelData implements DBIndexable
      */
     public function getDefaultValue(): mixed
     {
-        return $this->defaultVal;
+        return $this->defaultValue;
     }
 
     /**
@@ -222,7 +241,7 @@ abstract class DBField extends ModelData implements DBIndexable
      */
     public function setDefaultValue(mixed $defaultValue): static
     {
-        $this->defaultVal = $defaultValue;
+        $this->defaultValue = $defaultValue;
         return $this;
     }
 

src/ORM/FieldType/DBFloat.php

@@ -13,7 +13,7 @@ class DBFloat extends DBField
 {
     public function __construct(?string $name = null, float|int $defaultVal = 0)
     {
-        $this->defaultVal = is_float($defaultVal) ? $defaultVal : (float) 0;
+        $this->setDefaultValue(is_float($defaultVal) ? $defaultVal : (float) 0);
 
         parent::__construct($name);
     }
@@ -57,7 +57,7 @@ class DBFloat extends DBField
         return $field;
     }
 
-    public function nullValue(): ?int
+    public function nullValue(): int
     {
         return 0;
     }

src/ORM/FieldType/DBForeignKey.php

@@ -63,6 +63,11 @@ class DBForeignKey extends DBInt
         if ($record instanceof DataObject) {
             $this->object = $record;
         }
+        // Convert blank string to 0, this is sometimes required when calling DataObject::setCastedValue()
+        // after a form submission where the value is a blank string when no value is selected
+        if ($value === '') {
+            $value = 0;
+        }
         return parent::setValue($value, $record, $markChanged);
     }
 }

src/ORM/FieldType/DBInt.php

@@ -2,32 +2,46 @@
 
 namespace SilverStripe\ORM\FieldType;
 
+use SilverStripe\Core\Validation\FieldValidation\IntFieldValidator;
 use SilverStripe\Forms\FormField;
 use SilverStripe\Forms\NumericField;
 use SilverStripe\Model\List\ArrayList;
 use SilverStripe\ORM\DB;
 use SilverStripe\Model\List\SS_List;
 use SilverStripe\Model\ArrayData;
+use SilverStripe\Model\ModelData;
 
 /**
- * Represents a signed 32 bit integer field.
+ * Represents a signed 32 bit integer field
+ *
+ * Ints are always signed i.e. they can be negative
+ * Their range is -2147483648 to 2147483647
  */
 class DBInt extends DBField
 {
+    private static array $field_validators = [
+        IntFieldValidator::class
+    ];
+
     public function __construct(?string $name = null, int $defaultVal = 0)
     {
-        $this->defaultVal = is_int($defaultVal) ? $defaultVal : 0;
-
+        $this->setDefaultValue($defaultVal);
         parent::__construct($name);
     }
 
-    /**
-     * Ensure int values are always returned.
-     * This is for mis-configured databases that return strings.
-     */
-    public function getValue(): ?int
+    public function getField($fieldName): mixed
     {
-        return (int) $this->value;
+        return $this->value;
+    }
+
+    public function setValue(mixed $value, null|array|ModelData $record = null, bool $markChanged = true): static
+    {
+        parent::setValue($value, $record, $markChanged);
+        // Cast int like strings as ints
+        if (is_string($this->value) && preg_match('/^-?\d+$/', $this->value)) {
+            $this->value = (int) $value;
+        }
+        return $this;
     }
 
     /**
@@ -71,7 +85,7 @@ class DBInt extends DBField
         return NumericField::create($this->name, $title);
     }
 
-    public function nullValue(): ?int
+    public function nullValue(): int
     {
         return 0;
     }

src/ORM/FieldType/DBIp.php

@@ -0,0 +1,13 @@
+<?php
+
+namespace SilverStripe\ORM\FieldType;
+
+use SilverStripe\ORM\FieldType\DBVarchar;
+use SilverStripe\Core\Validation\FieldValidation\IpFieldValidator;
+
+class DBIp extends DBVarchar
+{
+    private static array $field_validators = [
+        IpFieldValidator::class,
+    ];
+}

src/ORM/FieldType/DBLocale.php

@@ -2,6 +2,7 @@
 
 namespace SilverStripe\ORM\FieldType;
 
+use SilverStripe\Core\Validation\FieldValidation\LocaleFieldValidator;
 use SilverStripe\i18n\i18n;
 
 /**
@@ -9,6 +10,10 @@ use SilverStripe\i18n\i18n;
  */
 class DBLocale extends DBVarchar
 {
+    private static array $field_validators = [
+        LocaleFieldValidator::class,
+    ];
+
     public function __construct(?string $name = null, int $size = 16)
     {
         parent::__construct($name, $size);

src/ORM/FieldType/DBMultiEnum.php

@@ -3,6 +3,8 @@
 namespace SilverStripe\ORM\FieldType;
 
 use SilverStripe\Core\Config\Config;
+use SilverStripe\Core\Validation\FieldValidation\EnumFieldValidator;
+use SilverStripe\Core\Validation\FieldValidation\MultiEnumFieldValidator;
 use SilverStripe\Forms\CheckboxSetField;
 use SilverStripe\Forms\MultiSelectField;
 use SilverStripe\ORM\Connect\MySQLDatabase;
@@ -13,6 +15,13 @@ use SilverStripe\ORM\DB;
  */
 class DBMultiEnum extends DBEnum
 {
+    private static array $field_validators = [
+        // disable parent field validator
+        EnumFieldValidator::class => null,
+        // enable multi enum field validator
+        MultiEnumFieldValidator::class => ['getEnum'],
+    ];
+
     public function __construct($name = null, $enum = null, $default = null)
     {
         // MultiEnum needs to take care of its own defaults
@@ -34,6 +43,15 @@ class DBMultiEnum extends DBEnum
         }
     }
 
+    public function getValueForValidation(): array
+    {
+        $value = parent::getValueForValidation();
+        if (is_array($value)) {
+            return $value;
+        }
+        return explode(',', (string) $value);
+    }
+
     public function requireField(): void
     {
         $charset = Config::inst()->get(MySQLDatabase::class, 'charset');

src/ORM/FieldType/DBPercentage.php

@@ -3,6 +3,7 @@
 namespace SilverStripe\ORM\FieldType;
 
 use SilverStripe\Model\ModelData;
+use SilverStripe\Core\Validation\FieldValidation\DecimalFieldValidator;
 
 /**
  * Represents a decimal field from 0-1 containing a percentage value.
@@ -17,6 +18,10 @@ use SilverStripe\Model\ModelData;
  */
 class DBPercentage extends DBDecimal
 {
+    private static array $field_validators = [
+        DecimalFieldValidator::class => ['getWholeSize', 'getDecimalSize', 'getMinValue', 'getMaxValue'],
+    ];
+
     /**
      * Create a new Decimal field.
      */
@@ -29,6 +34,16 @@ class DBPercentage extends DBDecimal
         parent::__construct($name, $precision + 1, $precision);
     }
 
+    public function getMinValue(): float
+    {
+        return 0.0;
+    }
+
+    public function getMaxValue(): float
+    {
+        return 1.0;
+    }
+
     /**
      * Returns the number, expressed as a percentage. For example, “36.30%”
      */

src/ORM/FieldType/DBPolymorphicForeignKey.php

@@ -5,12 +5,18 @@ namespace SilverStripe\ORM\FieldType;
 use SilverStripe\Forms\FormField;
 use SilverStripe\ORM\DataObject;
 use SilverStripe\Model\ModelData;
+use SilverStripe\Core\Validation\FieldValidation\CompositeFieldValidator;
 
 /**
  * A special ForeignKey class that handles relations with arbitrary class types
  */
 class DBPolymorphicForeignKey extends DBComposite
 {
+    private static array $field_validators = [
+        // Disable parent field validator
+        CompositeFieldValidator::class => null,
+    ];
+
     private static bool $index = true;
 
     private static array $composite_db = [

src/ORM/FieldType/DBString.php

@@ -2,11 +2,18 @@
 
 namespace SilverStripe\ORM\FieldType;
 
+use SilverStripe\Model\ModelData;
+use SilverStripe\Core\Validation\FieldValidation\StringFieldValidator;
+
 /**
  * An abstract base class for the string field types (i.e. Varchar and Text)
  */
 abstract class DBString extends DBField
 {
+    private static array $field_validators = [
+        StringFieldValidator::class,
+    ];
+
     private static array $casting = [
         'LimitCharacters' => 'Text',
         'LimitCharactersToClosestWord' => 'Text',
@@ -17,13 +24,14 @@ abstract class DBString extends DBField
     ];
 
     /**
-     * Set the default value for "nullify empty"
+     * Set the default value for "nullify empty" and 'default'
      *
      * {@inheritDoc}
      */
     public function __construct($name = null, $options = [])
     {
         $this->options['nullifyEmpty'] = true;
+        $this->options['default'] = '';
         parent::__construct($name, $options);
     }
 
@@ -82,6 +90,11 @@ abstract class DBString extends DBField
         return $value || (is_string($value) && strlen($value ?? ''));
     }
 
+    public function nullValue(): string
+    {
+        return '';
+    }
+
     public function prepValueForDB(mixed $value): array|string|null
     {
         // Cast non-empty value

src/ORM/FieldType/DBTime.php

@@ -11,6 +11,7 @@ use SilverStripe\ORM\DB;
 use SilverStripe\Security\Member;
 use SilverStripe\Security\Security;
 use SilverStripe\Model\ModelData;
+use SilverStripe\Core\Validation\FieldValidation\TimeFieldValidator;
 
 /**
  * Represents a column in the database with the type 'Time'.
@@ -26,17 +27,17 @@ class DBTime extends DBField
 {
     /**
      * Standard ISO format string for time in CLDR standard format
+     * This is equivalent to php date format "H:i:s" e.g. 09:30:00
      */
     public const ISO_TIME = 'HH:mm:ss';
 
+    private static array $field_validators = [
+        TimeFieldValidator::class,
+    ];
+
     public function setValue(mixed $value, null|array|ModelData $record = null, bool $markChanged = true): static
     {
         $value = $this->parseTime($value);
-        if ($value === false) {
-            throw new InvalidArgumentException(
-                'Invalid date passed. Use ' . $this->getISOFormat() . ' to prevent this error.'
-            );
-        }
         $this->value = $value;
         return $this;
     }

src/ORM/FieldType/DBUrl.php

@@ -0,0 +1,22 @@
+<?php
+
+namespace SilverStripe\ORM\FieldType;
+
+use SilverStripe\ORM\FieldType\DBVarchar;
+use SilverStripe\Core\Validation\FieldValidation\UrlFieldValidator;
+use SilverStripe\Forms\FormField;
+use SilverStripe\Forms\UrlField;
+
+class DBUrl extends DBVarchar
+{
+    private static array $field_validators = [
+        UrlFieldValidator::class,
+    ];
+
+    public function scaffoldFormField(?string $title = null, array $params = []): ?FormField
+    {
+        $field = UrlField::create($this->name, $title);
+        $field->setMaxLength($this->getSize());
+        return $field;
+    }
+}

src/ORM/FieldType/DBVarchar.php

@@ -8,6 +8,7 @@ use SilverStripe\Forms\NullableField;
 use SilverStripe\Forms\TextField;
 use SilverStripe\ORM\Connect\MySQLDatabase;
 use SilverStripe\ORM\DB;
+use SilverStripe\Core\Validation\FieldValidation\StringFieldValidator;
 
 /**
  * Class Varchar represents a variable-length string of up to 255 characters, designed to store raw text
@@ -18,6 +19,10 @@ use SilverStripe\ORM\DB;
  */
 class DBVarchar extends DBString
 {
+    private static array $field_validators = [
+        StringFieldValidator::class => [null, 'getSize'],
+    ];
+
     private static array $casting = [
         'Initial' => 'Text',
         'URL' => 'Text',

src/ORM/FieldType/DBYear.php

@@ -5,12 +5,23 @@ namespace SilverStripe\ORM\FieldType;
 use SilverStripe\Forms\DropdownField;
 use SilverStripe\Forms\FormField;
 use SilverStripe\ORM\DB;
+use SilverStripe\Model\ModelData;
+use SilverStripe\Core\Validation\FieldValidation\YearFieldValidator;
 
 /**
- * Represents a single year field.
+ * Represents a single year field
  */
 class DBYear extends DBField
 {
+    // MySQL year datatype supports years between 1901 and 2155
+    // https://dev.mysql.com/doc/refman/8.0/en/year.html
+    public const MIN_YEAR = 1901;
+    public const MAX_YEAR = 2155;
+
+    private static $field_validators = [
+        YearFieldValidator::class => ['getMinYear', 'getMaxYear'],
+    ];
+
     public function requireField(): void
     {
         $parts = ['datatype' => 'year', 'precision' => 4, 'arrayValue' => $this->arrayValue];
@@ -25,11 +36,56 @@ class DBYear extends DBField
         return $selectBox;
     }
 
+    public function setValue(mixed $value, null|array|ModelData $record = null, bool $markChanged = true): static
+    {
+        parent::setValue($value, $record, $markChanged);
+        // 0 is used to represent a null value, which will be stored as 0000 in MySQL
+        if ($this->value === '0000') {
+            $this->value = 0;
+        }
+        // shorthand for 2000 in MySQL
+        if ($this->value === '00') {
+            $this->value = 2000;
+        }
+        // convert string int to int
+        // string int and int are both valid in MySQL, though only use int internally
+        if (is_string($this->value) && preg_match('#^\d+$#', (string) $this->value)) {
+            $this->value = (int) $this->value;
+        }
+        if (!is_int($this->value)) {
+            return $this;
+        }
+        // shorthand for 2001-2069 in MySQL
+        if ($this->value >= 1 && $this->value <= 69) {
+            $this->value = 2000 + $this->value;
+        }
+        // shorthand for 1970-1999 in MySQL
+        if ($this->value >= 70 && $this->value <= 99) {
+            $this->value = 1900 + $this->value;
+        }
+        return $this;
+    }
+
+    public function nullValue(): int
+    {
+        return 0;
+    }
+
+    public function getMinYear(): int
+    {
+        return DBYear::MIN_YEAR;
+    }
+
+    public function getMaxYear(): int
+    {
+        return DBYear::MAX_YEAR;
+    }
+
     /**
      * Returns a list of default options that can
      * be used to populate a select box, or compare against
      * input values. Starts by default at the current year,
-     * and counts back to 1900.
+     * and counts back to 1901.
      *
      * @param int|null $start starting date to count down from
      * @param int|null $end end date to count down to
@@ -40,7 +96,7 @@ class DBYear extends DBField
             $start = (int) date('Y');
         }
         if (!$end) {
-            $end = 1900;
+            $end = DBYear::MIN_YEAR;
         }
         $years = [];
         for ($i = $start; $i >= $end; $i--) {

src/Security/Group.php

@@ -88,6 +88,8 @@ class Group extends DataObject
 
     private static $table_name = "Group";
 
+    private static bool $must_use_primary_db = true;
+
     private static $indexes = [
         'Title' => true,
         'Code' => true,

src/Security/LoginAttempt.php

@@ -50,6 +50,8 @@ class LoginAttempt extends DataObject
 
     private static $table_name = "LoginAttempt";
 
+    private static bool $must_use_primary_db = true;
+
     /**
      * @param bool $includerelations Indicate if the labels returned include relation fields
      * @return array

src/Security/Member.php

@@ -105,6 +105,8 @@ class Member extends DataObject
 
     private static $table_name = "Member";
 
+    private static bool $must_use_primary_db = true;
+
     private static $default_sort = '"Surname", "FirstName"';
 
     private static $indexes = [

src/Security/MemberPassword.php

@@ -27,6 +27,8 @@ class MemberPassword extends DataObject
 
     private static $table_name = "MemberPassword";
 
+    private static bool $must_use_primary_db = true;
+
     /**
      * Log a password change from the given member.
      * Call MemberPassword::log($this) from within Member whenever the password is changed.

src/Security/Permission.php

@@ -46,6 +46,8 @@ class Permission extends DataObject implements TemplateGlobalProvider, Resettabl
 
     private static $table_name = "Permission";
 
+    private static bool $must_use_primary_db = true;
+
     /**
      * This is the value to use for the "Type" field if a permission should be
      * granted.
@@ -233,7 +235,7 @@ class Permission extends DataObject implements TemplateGlobalProvider, Resettabl
         }
 
         // Raw SQL for efficiency
-        $permission = DB::prepared_query(
+        $permission = DB::withPrimary(fn() => DB::prepared_query(
             "SELECT \"ID\"
             FROM \"Permission\"
             WHERE (
@@ -249,7 +251,7 @@ class Permission extends DataObject implements TemplateGlobalProvider, Resettabl
                 $groupParams,
                 $argParams
             )
-        )->value();
+        )->value());
 
         if ($permission) {
             return $permission;
@@ -257,7 +259,7 @@ class Permission extends DataObject implements TemplateGlobalProvider, Resettabl
 
         // Strict checking disabled?
         if (!static::config()->strict_checking || !$strict) {
-            $hasPermission = DB::prepared_query(
+            $hasPermission = DB::withPrimary(fn() => DB::prepared_query(
                 "SELECT COUNT(*)
                 FROM \"Permission\"
                 WHERE (
@@ -265,7 +267,7 @@ class Permission extends DataObject implements TemplateGlobalProvider, Resettabl
                     \"Type\" = ?
                 )",
                 array_merge($codeParams, [Permission::GRANT_PERMISSION])
-            )->value();
+            )->value());
 
             if (!$hasPermission) {
                 return false;
@@ -288,7 +290,8 @@ class Permission extends DataObject implements TemplateGlobalProvider, Resettabl
         if ($groupList) {
             $groupCSV = implode(", ", $groupList);
 
-            $allowed = array_unique(DB::query("
+            $allowed = array_unique(
+                DB::withPrimary(fn() => DB::query("
                     SELECT \"Code\"
                     FROM \"Permission\"
                     WHERE \"Type\" = " . Permission::GRANT_PERMISSION . " AND \"GroupID\" IN ($groupCSV)
@@ -300,13 +303,16 @@ class Permission extends DataObject implements TemplateGlobalProvider, Resettabl
                     INNER JOIN \"PermissionRole\" PR ON PRC.\"RoleID\" = PR.\"ID\"
                     INNER JOIN \"Group_Roles\" GR ON GR.\"PermissionRoleID\" = PR.\"ID\"
                     WHERE \"GroupID\" IN ($groupCSV)
-			")->column() ?? []);
+                "))->column() ?? []
+            );
 
-            $denied = array_unique(DB::query("
+            $denied = array_unique(
+                DB::withPrimary(fn() => DB::query("
                     SELECT \"Code\"
                     FROM \"Permission\"
                     WHERE \"Type\" = " . Permission::DENY_PERMISSION . " AND \"GroupID\" IN ($groupCSV)
-			")->column() ?? []);
+                "))->column() ?? []
+            );
 
             return array_diff($allowed ?? [], $denied);
         }
@@ -584,7 +590,9 @@ class Permission extends DataObject implements TemplateGlobalProvider, Resettabl
                 $flatCodeArray[] = $code;
             }
         }
-        $otherPerms = DB::query("SELECT DISTINCT \"Code\" From \"Permission\" WHERE \"Code\" != ''")->column();
+        $otherPerms = DB::withPrimary(
+            fn() => DB::query("SELECT DISTINCT \"Code\" From \"Permission\" WHERE \"Code\" != ''")->column()
+        );
 
         if ($otherPerms) {
             foreach ($otherPerms as $otherPerm) {

src/Security/PermissionRole.php

@@ -40,6 +40,8 @@ class PermissionRole extends DataObject
 
     private static $table_name = "PermissionRole";
 
+    private static bool $must_use_primary_db = true;
+
     private static $default_sort = '"Title"';
 
     private static $singular_name = 'Role';

src/Security/PermissionRoleCode.php

@@ -24,6 +24,8 @@ class PermissionRoleCode extends DataObject
 
     private static $table_name = "PermissionRoleCode";
 
+    private static bool $must_use_primary_db = true;
+    
     private static $indexes = [
         "Code" => true,
     ];

src/Security/RememberLoginHash.php

@@ -44,6 +44,8 @@ class RememberLoginHash extends DataObject
 
     private static $table_name = "RememberLoginHash";
 
+    private static bool $must_use_primary_db = true;
+
     /**
      * Determines if logging out on one device also clears existing login tokens
      * on all other devices owned by the member.

src/Security/Security.php

@@ -437,6 +437,12 @@ class Security extends Controller implements TemplateGlobalProvider
      */
     public static function setCurrentUser($currentUser = null)
     {
+        // Always use the primary database and not a replica if a CMS user is logged in
+        // This is to ensure that when viewing content on the frontend it is always
+        // up to date i.e. not from an unsynced replica
+        if ($currentUser && Permission::checkMember($currentUser, 'CMS_ACCESS')) {
+            DB::setMustUsePrimary();
+        }
         Security::$currentUser = $currentUser;
     }
 

tests/php/Core/KernelTest.php

@@ -11,6 +11,10 @@ use SilverStripe\Core\Injector\Injector;
 use SilverStripe\Core\Injector\InjectorLoader;
 use SilverStripe\Core\Kernel;
 use SilverStripe\Dev\SapphireTest;
+use SilverStripe\Core\Environment;
+use ReflectionClass;
+use SilverStripe\ORM\DB;
+use ReflectionObject;
 
 class KernelTest extends SapphireTest
 {
@@ -81,4 +85,32 @@ class KernelTest extends SapphireTest
 
         $kernel->getConfigLoader()->getManifest();
     }
+    
+    public function testReplicaDatabaseVarsLoaded()
+    {
+        // Set environment variables for a fake replica database
+        Environment::setEnv('SS_DATABASE_SERVER_REPLICA_01', 'the-moon');
+        Environment::setEnv('SS_DATABASE_USERNAME_REPLICA_01', 'alien');
+        Environment::setEnv('SS_DATABASE_PASSWORD_REPLICA_01', 'hi_people');
+        // Get the CoreKernel
+        /** @var Kernel $kernel */
+        $kernel = Injector::inst()->get(Kernel::class);
+        /** @var CoreKernel $coreKernel */
+        $coreKernel = $kernel->nest();
+        $this->assertTrue(is_a($coreKernel, CoreKernel::class));
+        // Boot the database environment variables
+        $reflector = new ReflectionObject($coreKernel);
+        $method = $reflector->getMethod('bootDatabaseEnvVars');
+        $method->setAccessible(true);
+        $method->invoke($coreKernel);
+        // Assert DB config was updated
+        $default = DB::getConfig(DB::CONN_PRIMARY);
+        $configs = (new ReflectionClass(DB::class))->getStaticPropertyValue('configs');
+        $this->assertSame([
+            'type' => $default['type'],
+            'server' => 'the-moon',
+            'username' => 'alien',
+            'password' => 'hi_people',
+        ], $configs['replica_01']);
+    }
 }

tests/php/Core/Validation/FieldValidation/BigIntFieldValidatorTest.php

@@ -0,0 +1,75 @@
+<?php
+
+namespace SilverStripe\Core\Tests\Validation\FieldValidation;
+
+use SilverStripe\Dev\SapphireTest;
+use PHPUnit\Framework\Attributes\DataProvider;
+use SilverStripe\Core\Validation\FieldValidation\BigIntFieldValidator;
+
+class BigIntFieldValidatorTest extends SapphireTest
+{
+    public static function provideValidate(): array
+    {
+        return [
+            'valid-int' => [
+                'value' => 123,
+                'expected' => true,
+            ],
+            'valid-zero' => [
+                'value' => 0,
+                'expected' => true,
+            ],
+            'valid-negative-int' => [
+                'value' => -123,
+                'expected' => true,
+            ],
+            'valid-max-int' => [
+                'value' => 9223372036854775807,
+                'expected' => true,
+            ],
+            'valid-min-int' => [
+                'value' => '-9223372036854775808',
+                'expected' => true,
+            ],
+            // Note: cannot test out of range values as they casting them to int
+            // will change the value to PHP_INT_MIN/PHP_INT_MAX
+            'invalid-string-int' => [
+                'value' => '123',
+                'expected' => false,
+            ],
+            'invalid-float' => [
+                'value' => 123.45,
+                'expected' => false,
+            ],
+            'invalid-array' => [
+                'value' => [123],
+                'expected' => false,
+            ],
+            'invalid-null' => [
+                'value' => null,
+                'expected' => false,
+            ],
+            'invalid-true' => [
+                'value' => true,
+                'expected' => false,
+            ],
+            'invalid-false' => [
+                'value' => false,
+                'expected' => false,
+            ],
+        ];
+    }
+
+    #[DataProvider('provideValidate')]
+    public function testValidate(mixed $value, bool $expected): void
+    {
+        // On 64-bit systems, -9223372036854775808 will end up as a float
+        // however it works correctly when cast to an int
+        if ($value === '-9223372036854775808') {
+            $value = (int) $value;
+        }
+        $validator = new BigIntFieldValidator('MyField', $value);
+        $result = $validator->validate();
+        $this->assertSame($expected, $result->isValid());
+    }
+}

tests/php/Core/Validation/FieldValidation/BooleanFieldValidatorTest.php

@@ -0,0 +1,72 @@
+<?php
+
+namespace SilverStripe\Core\Tests\Validation\FieldValidation;
+
+use SilverStripe\Dev\SapphireTest;
+use PHPUnit\Framework\Attributes\DataProvider;
+use SilverStripe\Core\Validation\FieldValidation\BooleanFieldValidator;
+
+class BooleanFieldValidatorTest extends SapphireTest
+{
+    public static function provideValidate(): array
+    {
+        return [
+            'valid-int-1' => [
+                'value' => 1,
+                'expected' => true,
+            ],
+            'valid-int-0' => [
+                'value' => 0,
+                'expected' => true,
+            ],
+            'invvalid-true' => [
+                'value' => true,
+                'expected' => false,
+            ],
+            'invalid-false' => [
+                'value' => false,
+                'expected' => false,
+            ],
+            'invalid-string-1' => [
+                'value' => '1',
+                'expected' => false,
+            ],
+            'invalid-string-0' => [
+                'value' => '0',
+                'expected' => false,
+            ],
+            'invalid-string-true' => [
+                'value' => 'true',
+                'expected' => false,
+            ],
+            'invalid-string-false' => [
+                'value' => 'false',
+                'expected' => false,
+            ],
+            'invalid-null' => [
+                'value' => null,
+                'expected' => false,
+            ],
+            'invalid-string' => [
+                'value' => 'abc',
+                'expected' => false,
+            ],
+            'invalid-int' => [
+                'value' => 123,
+                'expected' => false,
+            ],
+            'invalid-array' => [
+                'value' => [],
+                'expected' => false,
+            ],
+        ];
+    }
+
+    #[DataProvider('provideValidate')]
+    public function testValidate(mixed $value, bool $expected): void
+    {
+        $validator = new BooleanFieldValidator('MyField', $value);
+        $result = $validator->validate();
+        $this->assertSame($expected, $result->isValid());
+    }
+}

tests/php/Core/Validation/FieldValidation/CompositeFieldValidatorTest.php

@@ -0,0 +1,97 @@
+<?php
+
+namespace SilverStripe\Core\Tests\Validation\FieldValidation;
+
+use InvalidArgumentException;
+use stdClass;
+use PHPUnit\Framework\Attributes\DataProvider;
+use SilverStripe\Dev\SapphireTest;
+use SilverStripe\Core\Validation\FieldValidation\CompositeFieldValidator;
+use SilverStripe\ORM\FieldType\DBBoolean;
+use SilverStripe\ORM\FieldType\DBVarchar;
+
+class CompositeFieldValidatorTest extends SapphireTest
+{
+    public static function provideValidate(): array
+    {
+        return [
+            'valid' => [
+                'valueBoolean' => true,
+                'valueString' => 'fish',
+                'valueIsNull' => false,
+                'exception' => null,
+                'expected' => true,
+            ],
+            'exception-not-iterable' => [
+                'valueBoolean' => true,
+                'valueString' => 'not-iterable',
+                'valueIsNull' => false,
+                'exception' => InvalidArgumentException::class,
+                'expected' => true,
+            ],
+            'exception-not-field-validator' => [
+                'valueBoolean' => true,
+                'valueString' => 'no-field-validation',
+                'valueIsNull' => false,
+                'exception' => InvalidArgumentException::class,
+                'expected' => true,
+            ],
+            'exception-do-not-skip-null' => [
+                'valueBoolean' => true,
+                'valueString' => 'fish',
+                'valueIsNull' => true,
+                'exception' => InvalidArgumentException::class,
+                'expected' => true,
+            ],
+            'invalid-bool-field' => [
+                'valueBoolean' => 'dog',
+                'valueString' => 'fish',
+                'valueIsNull' => false,
+                'exception' => null,
+                'expected' => false,
+            ],
+            'invalid-string-field' => [
+                'valueBoolean' => true,
+                'valueString' => 456.789,
+                'valueIsNull' => false,
+                'exception' => null,
+                'expected' => false,
+            ],
+        ];
+    }
+
+    #[DataProvider('provideValidate')]
+    public function testValidate(
+        mixed $valueBoolean,
+        mixed $valueString,
+        bool $valueIsNull,
+        ?string $exception,
+        bool $expected
+    ): void {
+        if ($exception) {
+            $this->expectException($exception);
+        }
+        if ($valueIsNull) {
+            $iterable = null;
+        } else {
+            $booleanField = new DBBoolean('BooleanField');
+            $booleanField->setValue($valueBoolean);
+            if ($exception && $valueString === 'no-field-validation') {
+                $stringField = new stdClass();
+            } else {
+                $stringField = new DBVarchar('StringField');
+                $stringField->setValue($valueString);
+            }
+            if ($exception && $valueString === 'not-iterable') {
+                $iterable = 'banana';
+            } else {
+                $iterable = [$booleanField, $stringField];
+            }
+        }
+        $validator = new CompositeFieldValidator('MyField', $iterable);
+        $result = $validator->validate();
+        if (!$exception) {
+            $this->assertSame($expected, $result->isValid());
+        }
+    }
+}

tests/php/Core/Validation/FieldValidation/DateFieldValidatorTest.php

@@ -0,0 +1,48 @@
+<?php
+
+namespace SilverStripe\Core\Tests\Validation\FieldValidation;
+
+use SilverStripe\Dev\SapphireTest;
+use PHPUnit\Framework\Attributes\DataProvider;
+use SilverStripe\Core\Validation\FieldValidation\DateFieldValidator;
+
+class DateFieldValidatorTest extends SapphireTest
+{
+    public static function provideValidate(): array
+    {
+        return [
+            'valid' => [
+                'value' => '2020-09-15',
+                'expected' => true,
+            ],
+            'invalid' => [
+                'value' => '2020-02-30',
+                'expected' => false,
+            ],
+            'invalid-wrong-format' => [
+                'value' => '15-09-2020',
+                'expected' => false,
+            ],
+            'invalid-date-time' => [
+                'value' => '2020-09-15 13:34:56',
+                'expected' => false,
+            ],
+            'invalid-time' => [
+                'value' => '13:34:56',
+                'expected' => false,
+            ],
+            'invalid-null' => [
+                'value' => null,
+                'expected' => false,
+            ],
+        ];
+    }
+
+    #[DataProvider('provideValidate')]
+    public function testValidate(mixed $value, bool $expected): void
+    {
+        $validator = new DateFieldValidator('MyField', $value);
+        $result = $validator->validate();
+        $this->assertSame($expected, $result->isValid());
+    }
+}

tests/php/Core/Validation/FieldValidation/DatetimeFieldValidatorTest.php

@@ -0,0 +1,52 @@
+<?php
+
+namespace SilverStripe\Core\Tests\Validation\FieldValidation;
+
+use SilverStripe\Dev\SapphireTest;
+use PHPUnit\Framework\Attributes\DataProvider;
+use SilverStripe\Core\Validation\FieldValidation\DatetimeFieldValidator;
+
+class DatetimeFieldValidatorTest extends SapphireTest
+{
+    public static function provideValidate(): array
+    {
+        return [
+            'valid' => [
+                'value' => '2020-09-15 13:34:56',
+                'expected' => true,
+            ],
+            'invalid-date' => [
+                'value' => '2020-02-30 13:34:56',
+                'expected' => false,
+            ],
+            'invalid-time' => [
+                'value' => '2020-02-15 13:99:56',
+                'expected' => false,
+            ],
+            'invalid-wrong-format' => [
+                'value' => '15-09-2020 13:34:56',
+                'expected' => false,
+            ],
+            'invalid-date-only' => [
+                'value' => '2020-09-15',
+                'expected' => false,
+            ],
+            'invalid-time-only' => [
+                'value' => '13:34:56',
+                'expected' => false,
+            ],
+            'invalid-null' => [
+                'value' => null,
+                'expected' => false,
+            ],
+        ];
+    }
+
+    #[DataProvider('provideValidate')]
+    public function testValidate(mixed $value, bool $expected): void
+    {
+        $validator = new DatetimeFieldValidator('MyField', $value);
+        $result = $validator->validate();
+        $this->assertSame($expected, $result->isValid());
+    }
+}

tests/php/Core/Validation/FieldValidation/DecimalFieldValidatorTest.php

@@ -0,0 +1,138 @@
+<?php
+
+namespace SilverStripe\Core\Tests\Validation\FieldValidation;
+
+use SilverStripe\Dev\SapphireTest;
+use PHPUnit\Framework\Attributes\DataProvider;
+use SilverStripe\Core\Validation\FieldValidation\DecimalFieldValidator;
+
+class DecimalFieldValidatorTest extends SapphireTest
+{
+    public static function provideValidate(): array
+    {
+        return [
+            'valid' => [
+                'value' => 123.45,
+                'wholeSize' => 5,
+                'decimalSize' => 2,
+                'expected' => true,
+            ],
+            'valid-negative' => [
+                'value' => -123.45,
+                'wholeSize' => 5,
+                'decimalSize' => 2,
+                'expected' => true,
+            ],
+            'valid-zero' => [
+                'value' => 0,
+                'wholeSize' => 5,
+                'decimalSize' => 2,
+                'expected' => true,
+            ],
+            'valid-rounded-dp' => [
+                'value' => 123.456,
+                'wholeSize' => 5,
+                'decimalSize' => 2,
+                'expected' => true,
+            ],
+            'valid-rounded-up' => [
+                'value' => 123.999,
+                'wholeSize' => 5,
+                'decimalSize' => 2,
+                'expected' => true,
+            ],
+            'valid-int' => [
+                'value' => 123,
+                'wholeSize' => 5,
+                'decimalSize' => 2,
+                'expected' => true,
+            ],
+            'valid-negative-int' => [
+                'value' => -123,
+                'wholeSize' => 5,
+                'decimalSize' => 2,
+                'expected' => true,
+            ],
+            'valid-max' => [
+                'value' => 999.99,
+                'wholeSize' => 5,
+                'decimalSize' => 2,
+                'expected' => true,
+            ],
+            'valid-max-negative' => [
+                'value' => -999.99,
+                'wholeSize' => 5,
+                'decimalSize' => 2,
+                'expected' => true,
+            ],
+            'invalid-rounded-to-6-digts' => [
+                'value' => 999.999,
+                'wholeSize' => 5,
+                'decimalSize' => 2,
+                'expected' => false,
+            ],
+            'invalid-too-long' => [
+                'value' => 1234.56,
+                'wholeSize' => 5,
+                'decimalSize' => 2,
+                'expected' => false,
+            ],
+            'invalid-too-long-3dp' => [
+                'value' => 123.456,
+                'wholeSize' => 5,
+                'decimalSize' => 3,
+                'expected' => false,
+            ],
+            'invalid-too-long-1dp' => [
+                'value' => 123.4,
+                'wholeSize' => 5,
+                'decimalSize' => 3,
+                'expected' => false,
+            ],
+            'invalid-too-long-int' => [
+                'value' => 123,
+                'wholeSize' => 5,
+                'decimalSize' => 3,
+                'expected' => false,
+            ],
+            'invalid-string' => [
+                'value' => '123.45',
+                'wholeSize' => 5,
+                'decimalSize' => 2,
+                'expected' => false,
+            ],
+            'invalid-null' => [
+                'value' => null,
+                'wholeSize' => 5,
+                'decimalSize' => 2,
+                'expected' => false,
+            ],
+            'invalid-true' => [
+                'value' => true,
+                'wholeSize' => 5,
+                'decimalSize' => 2,
+                'expected' => false,
+            ],
+            'invalid-false' => [
+                'value' => false,
+                'wholeSize' => 5,
+                'decimalSize' => 2,
+                'expected' => false,
+            ],
+            'invalid-array' => [
+                'value' => [123.45],
+                'wholeSize' => 5,
+                'decimalSize' => 2,
+                'expected' => false,
+            ],
+        ];
+    }
+
+    #[DataProvider('provideValidate')]
+    public function testValidate(mixed $value, int $wholeSize, int $decimalSize, bool $expected): void
+    {
+        $validator = new DecimalFieldValidator('MyField', $value, $wholeSize, $decimalSize);
+        $result = $validator->validate();
+        $this->assertSame($expected, $result->isValid());
+    }
+}

tests/php/Core/Validation/FieldValidation/EmailFieldValidatorTest.php

@@ -0,0 +1,37 @@
+<?php
+
+namespace SilverStripe\Core\Tests\Validation\FieldValidation;
+
+use SilverStripe\Dev\SapphireTest;
+use PHPUnit\Framework\Attributes\DataProvider;
+use SilverStripe\Core\Validation\FieldValidation\EmailFieldValidator;
+
+class EmailFieldValidatorTest extends SapphireTest
+{
+    public static function provideValidate(): array
+    {
+        // Using symfony/validator for implementation so only smoke testing
+        return [
+            'valid' => [
+                'value' => 'test@example.com',
+                'expected' => true,
+            ],
+            'invalid' => [
+                'value' => 'fish',
+                'expected' => false,
+            ],
+            'invalid-null' => [
+                'value' => null,
+                'expected' => false,
+            ],
+        ];
+    }
+
+    #[DataProvider('provideValidate')]
+    public function testValidate(mixed $value, bool $expected): void
+    {
+        $validator = new EmailFieldValidator('MyField', $value);
+        $result = $validator->validate();
+        $this->assertSame($expected, $result->isValid());
+    }
+}

tests/php/Core/Validation/FieldValidation/EnumFieldValidatorTest.php

@@ -0,0 +1,54 @@
+<?php
+
+namespace SilverStripe\Core\Tests\Validation\FieldValidation;
+
+use SilverStripe\Dev\SapphireTest;
+use PHPUnit\Framework\Attributes\DataProvider;
+use SilverStripe\Core\Validation\FieldValidation\EnumFieldValidator;
+
+class EnumFieldValidatorTest extends SapphireTest
+{
+    public static function provideValidate(): array
+    {
+        return [
+            'valid-string' => [
+                'value' => 'cat',
+                'allowedValues' => ['cat', 'dog'],
+                'expected' => true,
+            ],
+            'valid-int' => [
+                'value' => 123,
+                'allowedValues' => [123, 456],
+                'expected' => true,
+            ],
+            'invalid' => [
+                'value' => 'fish',
+                'allowedValues' => ['cat', 'dog'],
+                'expected' => false,
+            ],
+            'invalid-none' => [
+                'value' => '',
+                'allowedValues' => ['cat', 'dog'],
+                'expected' => false,
+            ],
+            'invalid-null' => [
+                'value' => null,
+                'allowedValues' => ['cat', 'dog'],
+                'expected' => false,
+            ],
+            'invalid-strict' => [
+                'value' => '123',
+                'allowedValues' => [123, 456],
+                'expected' => false,
+            ],
+        ];
+    }
+
+    #[DataProvider('provideValidate')]
+    public function testValidate(mixed $value, array $allowedValues, bool $expected): void
+    {
+        $validator = new EnumFieldValidator('MyField', $value, $allowedValues);
+        $result = $validator->validate();
+        $this->assertSame($expected, $result->isValid());
+    }
+}

tests/php/Core/Validation/FieldValidation/IntFieldValidatorTest.php

@@ -0,0 +1,76 @@
+<?php
+
+namespace SilverStripe\Core\Tests\Validation\FieldValidation;
+
+use SilverStripe\Dev\SapphireTest;
+use PHPUnit\Framework\Attributes\DataProvider;
+use SilverStripe\Core\Validation\FieldValidation\IntFieldValidator;
+
+class IntFieldValidatorTest extends SapphireTest
+{
+    public static function provideValidate(): array
+    {
+        return [
+            'valid-int' => [
+                'value' => 123,
+                'expected' => true,
+            ],
+            'valid-zero' => [
+                'value' => 0,
+                'expected' => true,
+            ],
+            'valid-negative-int' => [
+                'value' => -123,
+                'expected' => true,
+            ],
+            'valid-max-int' => [
+                'value' => 2147483647,
+                'expected' => true,
+            ],
+            'valid-min-int' => [
+                'value' => -2147483648,
+                'expected' => true,
+            ],
+            'invalid-out-of-bounds' => [
+                'value' => 2147483648,
+                'expected' => false,
+            ],
+            'invalid-out-of-negative-bounds' => [
+                'value' => -2147483649,
+                'expected' => false,
+            ],
+            'invalid-string-int' => [
+                'value' => '123',
+                'expected' => false,
+            ],
+            'invalid-float' => [
+                'value' => 123.45,
+                'expected' => false,
+            ],
+            'invalid-array' => [
+                'value' => [123],
+                'expected' => false,
+            ],
+            'invalid-null' => [
+                'value' => null,
+                'expected' => false,
+            ],
+            'invalid-true' => [
+                'value' => true,
+                'expected' => false,
+            ],
+            'invalid-false' => [
+                'value' => false,
+                'expected' => false,
+            ],
+        ];
+    }
+
+    #[DataProvider('provideValidate')]
+    public function testValidate(mixed $value, bool $expected): void
+    {
+        $validator = new IntFieldValidator('MyField', $value);
+        $result = $validator->validate();
+        $this->assertSame($expected, $result->isValid());
+    }
+}

tests/php/Core/Validation/FieldValidation/IpFieldValidatorTest.php

@@ -0,0 +1,45 @@
+<?php
+
+namespace SilverStripe\Core\Tests\Validation\FieldValidation;
+
+use SilverStripe\Dev\SapphireTest;
+use PHPUnit\Framework\Attributes\DataProvider;
+use SilverStripe\Core\Validation\FieldValidation\IpFieldValidator;
+
+class IpFieldValidatorTest extends SapphireTest
+{
+    public static function provideValidate(): array
+    {
+        // Using symfony/validator for implementation so only smoke testing
+        return [
+            'valid-ipv4' => [
+                'value' => '127.0.0.1',
+                'expected' => true,
+            ],
+            'valid-ipv6' => [
+                'value' => '0:0:0:0:0:0:0:1',
+                'expected' => true,
+            ],
+            'valid-ipv6-short' => [
+                'value' => '::1',
+                'expected' => true,
+            ],
+            'invalid' => [
+                'value' => '12345',
+                'expected' => false,
+            ],
+            'invalid-null' => [
+                'value' => null,
+                'expected' => false,
+            ],
+        ];
+    }
+
+    #[DataProvider('provideValidate')]
+    public function testValidate(mixed $value, bool $expected): void
+    {
+        $validator = new IpFieldValidator('MyField', $value);
+        $result = $validator->validate();
+        $this->assertSame($expected, $result->isValid());
+    }
+}

tests/php/Core/Validation/FieldValidation/LocaleFieldValidatorTest.php

@@ -0,0 +1,61 @@
+<?php
+
+namespace SilverStripe\Core\Tests\Validation\FieldValidation;
+
+use SilverStripe\Dev\SapphireTest;
+use PHPUnit\Framework\Attributes\DataProvider;
+use SilverStripe\Core\Validation\FieldValidation\LocaleFieldValidator;
+
+class LocaleFieldValidatorTest extends SapphireTest
+{
+    public static function provideValidate(): array
+    {
+        // Using symfony/validator for implementation so only smoke testing
+        return [
+            'valid' => [
+                'value' => 'de_DE',
+                'expected' => true,
+            ],
+            'valid-dash' => [
+                'value' => 'de-DE',
+                'expected' => true,
+            ],
+            'valid-short' => [
+                'value' => 'de',
+                'expected' => true,
+            ],
+            'invalid' => [
+                'value' => 'zz_ZZ',
+                'expected' => false,
+            ],
+            'invalid-dash' => [
+                'value' => 'zz-ZZ',
+                'expected' => false,
+            ],
+            'invalid-short' => [
+                'value' => 'zz',
+                'expected' => false,
+            ],
+            'invalid-dashes' => [
+                'value' => '-----',
+                'expected' => false,
+            ],
+            'invalid-donut' => [
+                'value' => 'donut',
+                'expected' => false,
+            ],
+            'invalid-null' => [
+                'value' => null,
+                'expected' => false,
+            ],
+        ];
+    }
+
+    #[DataProvider('provideValidate')]
+    public function testValidate(mixed $value, bool $expected): void
+    {
+        $validator = new LocaleFieldValidator('MyField', $value);
+        $result = $validator->validate();
+        $this->assertSame($expected, $result->isValid());
+    }
+}

tests/php/Core/Validation/FieldValidation/MultiEnumFieldValidatorTest.php

@@ -0,0 +1,84 @@
+<?php
+
+namespace SilverStripe\Core\Tests\Validation\FieldValidation;
+
+use InvalidArgumentException;
+use SilverStripe\Dev\SapphireTest;
+use PHPUnit\Framework\Attributes\DataProvider;
+use SilverStripe\Core\Validation\FieldValidation\MultiEnumFieldValidator;
+
+class MultiEnumFieldValidatorTest extends SapphireTest
+{
+    public static function provideValidate(): array
+    {
+        return [
+            'valid-string' => [
+                'value' => ['cat'],
+                'allowedValues' => ['cat', 'dog'],
+                'exception' => false,
+                'expected' => true,
+            ],
+            'valid-multi-string' => [
+                'value' => ['cat', 'dog'],
+                'allowedValues' => ['cat', 'dog'],
+                'exception' => false,
+                'expected' => true,
+            ],
+            'valid-none' => [
+                'value' => [],
+                'allowedValues' => ['cat', 'dog'],
+                'exception' => false,
+                'expected' => true,
+            ],
+            'valid-int' => [
+                'value' => [123],
+                'allowedValues' => [123, 456],
+                'exception' => false,
+                'expected' => true,
+            ],
+            'exception-not-array' => [
+                'value' => 'cat,dog',
+                'allowedValues' => ['cat', 'dog'],
+                'exception' => true,
+                'expected' => false,
+            ],
+            'invalid' => [
+                'value' => ['fish'],
+                'allowedValues' => ['cat', 'dog'],
+                'exception' => false,
+                'expected' => false,
+            ],
+            'invalid-null' => [
+                'value' => [null],
+                'allowedValues' => ['cat', 'dog'],
+                'exception' => false,
+                'expected' => false,
+            ],
+            'invalid-multi' => [
+                'value' => ['dog', 'fish'],
+                'allowedValues' => ['cat', 'dog'],
+                'exception' => false,
+                'expected' => false,
+            ],
+            'invalid-strict' => [
+                'value' => ['123'],
+                'allowedValues' => [123, 456],
+                'exception' => false,
+                'expected' => false,
+            ],
+        ];
+    }
+
+    #[DataProvider('provideValidate')]
+    public function testValidate(mixed $value, array $allowedValues, bool $exception, bool $expected): void
+    {
+        if ($exception) {
+            $this->expectException(InvalidArgumentException::class);
+        }
+        $validator = new MultiEnumFieldValidator('MyField', $value, $allowedValues);
+        $result = $validator->validate();
+        if (!$exception) {
+            $this->assertSame($expected, $result->isValid());
+        }
+    }
+}

tests/php/Core/Validation/FieldValidation/NumericFieldValidatorTest.php

@@ -0,0 +1,80 @@
+<?php
+
+namespace SilverStripe\Core\Tests\Validation\FieldValidation;
+
+use SilverStripe\Dev\SapphireTest;
+use PHPUnit\Framework\Attributes\DataProvider;
+use SilverStripe\Core\Validation\FieldValidation\NumericFieldValidator;
+
+class NumericFieldValidatorTest extends SapphireTest
+{
+    public static function provideValidate(): array
+    {
+        return [
+            'valid-int' => [
+                'value' => 123,
+                'expected' => true,
+            ],
+            'valid-zero' => [
+                'value' => 0,
+                'expected' => true,
+            ],
+            'valid-negative-int' => [
+                'value' => -123,
+                'expected' => true,
+            ],
+            'valid-float' => [
+                'value' => 123.45,
+                'expected' => true,
+            ],
+            'valid-negative-float' => [
+                'value' => -123.45,
+                'expected' => true,
+            ],
+            'valid-max-int' => [
+                'value' => PHP_INT_MAX,
+                'expected' => true,
+            ],
+            'valid-min-int' => [
+                'value' => PHP_INT_MIN,
+                'expected' => true,
+            ],
+            'valid-max-float' => [
+                'value' => PHP_FLOAT_MAX,
+                'expected' => true,
+            ],
+            'valid-min-float' => [
+                'value' => PHP_FLOAT_MIN,
+                'expected' => true,
+            ],
+            'invalid-string' => [
+                'value' => '123',
+                'expected' => false,
+            ],
+            'invalid-array' => [
+                'value' => [123],
+                'expected' => false,
+            ],
+            'invalid-null' => [
+                'value' => null,
+                'expected' => false,
+            ],
+            'invalid-true' => [
+                'value' => true,
+                'expected' => false,
+            ],
+            'invalid-false' => [
+                'value' => false,
+                'expected' => false,
+            ],
+        ];
+    }
+
+    #[DataProvider('provideValidate')]
+    public function testValidate(mixed $value, bool $expected): void
+    {
+        $validator = new NumericFieldValidator('MyField', $value);
+        $result = $validator->validate();
+        $this->assertSame($expected, $result->isValid());
+    }
+}

tests/php/Core/Validation/FieldValidation/StringFieldValidatorTest.php

@@ -0,0 +1,149 @@
+<?php
+
+namespace SilverStripe\Core\Tests\Validation\FieldValidation;
+
+use InvalidArgumentException;
+use PHPUnit\Framework\Attributes\DataProvider;
+use SilverStripe\Core\Validation\FieldValidation\StringFieldValidator;
+use SilverStripe\Dev\SapphireTest;
+
+class StringFieldValidatorTest extends SapphireTest
+{
+    public static function provideValidate(): array
+    {
+        return [
+            'valid-no-limit' => [
+                'value' => 'fish',
+                'minLength' => null,
+                'maxLength' => null,
+                'exception' => false,
+                'expected' => true,
+            ],
+            'valid-blank' => [
+                'value' => '',
+                'minLength' => null,
+                'maxLength' => null,
+                'exception' => false,
+                'expected' => true,
+            ],
+            'valid-blank-when-min' => [
+                'value' => '',
+                'minLength' => 5,
+                'maxLength' => null,
+                'exception' => false,
+                'expected' => true,
+            ],
+            'valid-max' => [
+                'value' => 'fish',
+                'minLength' => 0,
+                'maxLength' => 4,
+                'exception' => false,
+                'expected' => true,
+            ],
+            'valid-less-than-max-null-min' => [
+                'value' => 'fish',
+                'minLength' => null,
+                'maxLength' => 4,
+                'exception' => false,
+                'expected' => true,
+            ],
+            'valid-less-than-max-unicode' => [
+                'value' => '☕☕☕☕',
+                'minLength' => 0,
+                'maxLength' => 4,
+                'exception' => false,
+                'expected' => true,
+            ],
+            'exception-negative-min' => [
+                'value' => 'fish',
+                'minLength' => -1,
+                'maxLength' => null,
+                'exception' => true,
+                'expected' => false,
+            ],
+            'invalid-below-min' => [
+                'value' => 'fish',
+                'minLength' => 5,
+                'maxLength' => null,
+                'exception' => false,
+                'expected' => false,
+            ],
+            'invalid-below-min-unicode' => [
+                'value' => '☕☕☕☕',
+                'minLength' => 5,
+                'maxLength' => null,
+                'exception' => false,
+                'expected' => false,
+            ],
+            'invalid-above-min' => [
+                'value' => 'fish',
+                'minLength' => 0,
+                'maxLength' => 3,
+                'exception' => false,
+                'expected' => false,
+            ],
+            'invalid-above-min-unicode' => [
+                'value' => '☕☕☕☕',
+                'minLength' => 0,
+                'maxLength' => 3,
+                'exception' => false,
+                'expected' => false,
+            ],
+            'invalid-int' => [
+                'value' => 123,
+                'minLength' => null,
+                'maxLength' => null,
+                'exception' => false,
+                'expected' => false,
+            ],
+            'invalid-float' => [
+                'value' => 123.56,
+                'minLength' => null,
+                'maxLength' => null,
+                'exception' => false,
+                'expected' => false,
+            ],
+            'invalid-true' => [
+                'value' => true,
+                'minLength' => null,
+                'maxLength' => null,
+                'exception' => false,
+                'expected' => false,
+            ],
+            'invalid-false' => [
+                'value' => false,
+                'minLength' => null,
+                'maxLength' => null,
+                'exception' => false,
+                'expected' => false,
+            ],
+            'invalid-null' => [
+                'value' => null,
+                'minLength' => null,
+                'maxLength' => null,
+                'exception' => false,
+                'expected' => false,
+            ],
+            'invalid-array' => [
+                'value' => ['fish'],
+                'minLength' => null,
+                'maxLength' => null,
+                'exception' => false,
+                'expected' => false,
+            ],
+        ];
+    }
+
+    #[DataProvider('provideValidate')]
+    public function testValidate(mixed $value, ?int $minLength, ?int $maxLength, bool $exception, bool $expected): void
+    {
+        if ($exception) {
+            $this->expectException(InvalidArgumentException::class);
+        }
+        $validator = new StringFieldValidator('MyField', $value, $minLength, $maxLength);
+        $result = $validator->validate();
+        if (!$exception) {
+            $this->assertSame($expected, $result->isValid());
+        }
+    }
+}

tests/php/Core/Validation/FieldValidation/TimeFieldValidatorTest.php

@@ -0,0 +1,48 @@
+<?php
+
+namespace SilverStripe\Core\Tests\Validation\FieldValidation;
+
+use SilverStripe\Dev\SapphireTest;
+use PHPUnit\Framework\Attributes\DataProvider;
+use SilverStripe\Core\Validation\FieldValidation\TimeFieldValidator;
+
+class TimeFieldValidatorTest extends SapphireTest
+{
+    public static function provideValidate(): array
+    {
+        return [
+            'valid' => [
+                'value' => '13:34:56',
+                'expected' => true,
+            ],
+            'invalid' => [
+                'value' => '13:99:56',
+                'expected' => false,
+            ],
+            'invalid-wrong-format' => [
+                'value' => '13-34-56',
+                'expected' => false,
+            ],
+            'invalid-date-time' => [
+                'value' => '2020-09-15 13:34:56',
+                'expected' => false,
+            ],
+            'invalid-date' => [
+                'value' => '2020-09-15',
+                'expected' => false,
+            ],
+            'invalid-null' => [
+                'value' => null,
+                'expected' => false,
+            ],
+        ];
+    }
+
+    #[DataProvider('provideValidate')]
+    public function testValidate(mixed $value, bool $expected): void
+    {
+        $validator = new TimeFieldValidator('MyField', $value);
+        $result = $validator->validate();
+        $this->assertSame($expected, $result->isValid());
+    }
+}

tests/php/Core/Validation/FieldValidation/UrlFieldValidatorTest.php

@@ -0,0 +1,45 @@
+<?php
+
+namespace SilverStripe\Core\Tests\Validation\FieldValidation;
+
+use SilverStripe\Dev\SapphireTest;
+use PHPUnit\Framework\Attributes\DataProvider;
+use SilverStripe\Core\Validation\FieldValidation\UrlFieldValidator;
+
+class UrlFieldValidatorTest extends SapphireTest
+{
+    public static function provideValidate(): array
+    {
+        // Using symfony/validator for implementation so only smoke testing
+        return [
+            'valid-https' => [
+                'value' => 'https://www.example.com',
+                'expected' => true,
+            ],
+            'valid-http' => [
+                'value' => 'https://www.example.com',
+                'expected' => true,
+            ],
+            'invalid-ftp' => [
+                'value' => 'ftp://www.example.com',
+                'expected' => false,
+            ],
+            'invalid-no-scheme' => [
+                'value' => 'www.example.com',
+                'expected' => false,
+            ],
+            'invalid-null' => [
+                'value' => null,
+                'expected' => false,
+            ],
+        ];
+    }
+
+    #[DataProvider('provideValidate')]
+    public function testValidate(mixed $value, bool $expected): void
+    {
+        $validator = new UrlFieldValidator('MyField', $value);
+        $result = $validator->validate();
+        $this->assertSame($expected, $result->isValid());
+    }
+}

tests/php/Core/Validation/FieldValidation/YearFieldValidatorTest.php

@@ -0,0 +1,43 @@
+<?php
+
+namespace SilverStripe\Core\Tests\Validation\FieldValidation;
+
+use SilverStripe\Dev\SapphireTest;
+use PHPUnit\Framework\Attributes\DataProvider;
+use SilverStripe\Core\Validation\FieldValidation\YearFieldValidator;
+use SilverStripe\ORM\FieldType\DBYear;
+
+class YearFieldValidatorTest extends SapphireTest
+{
+    public static function provideValidate(): array
+    {
+        // YearFieldValidator extends IntFieldValidator so only testing a subset
+        // of possible values here
+        return [
+            'valid-int' => [
+                'value' => 2021,
+                'expected' => true,
+            ],
+            'valid-zero' => [
+                'value' => 0,
+                'expected' => true,
+            ],
+            'invalid-out-of-range-low' => [
+                'value' => 1850,
+                'expected' => false,
+            ],
+            'invalid-out-of-range-high' => [
+                'value' => 3000,
+                'expected' => false,
+            ],
+        ];
+    }
+
+    #[DataProvider('provideValidate')]
+    public function testValidate(mixed $value, bool $expected): void
+    {
+        $validator = new YearFieldValidator('MyField', $value, DBYear::MIN_YEAR, DBYear::MAX_YEAR);
+        $result = $validator->validate();
+        $this->assertSame($expected, $result->isValid());
+    }
+}

tests/php/Forms/TextFieldTest.php

@@ -6,6 +6,7 @@ use SilverStripe\Dev\SapphireTest;
 use SilverStripe\Forms\TextField;
 use SilverStripe\Forms\RequiredFields;
 use SilverStripe\Forms\Tip;
+use PHPUnit\Framework\Attributes\DataProvider;
 
 class TextFieldTest extends SapphireTest
 {
@@ -45,4 +46,42 @@ class TextFieldTest extends SapphireTest
         $textField->setTip(new Tip('TestTip'));
         $this->assertArrayHasKey('tip', $textField->getSchemaDataDefaults());
     }
+
+    public static function provideSetValue(): array
+    {
+        return [
+            'string' => [
+                'value' => 'fish',
+                'expected' => 'fish',
+            ],
+            'string-blank' => [
+                'value' => '',
+                'expected' => '',
+            ],
+            'null' => [
+                'value' => null,
+                'expected' => '',
+            ],
+            'zero' => [
+                'value' => 0,
+                'expected' => 0,
+            ],
+            'true' => [
+                'value' => true,
+                'expected' => true,
+            ],
+            'false' => [
+                'value' => false,
+                'expected' => false,
+            ],
+        ];
+    }
+
+    #[DataProvider('provideSetValue')]
+    public function testSetValue(mixed $value, mixed $expected): void
+    {
+        $field = new TextField('TestField');
+        $field->setValue($value);
+        $this->assertSame($expected, $field->getValue());
+    }
 }

tests/php/Forms/UrlFieldTest.php

@@ -89,4 +89,23 @@ class UrlFieldTest extends SapphireTest
         $expectedCount = $valid ? 0 : 1;
         $this->assertEquals($expectedCount, count($validator->getErrors()));
     }
+
+    public function testAllowedProtocols(): void
+    {
+        $field = new UrlField('MyUrl');
+        // Defaults should be http and https
+        $this->assertSame(['https', 'http'], $field->getAllowedProtocols());
+
+        // Defaults change with config, and ignore keys
+        UrlField::config()->set('default_protocols', ['my-key' => 'ftp']);
+        $this->assertSame(['ftp'], $field->getAllowedProtocols());
+
+        // Can set explicit protocols - again keys are ignored
+        $field->setAllowedProtocols(['http', 'key' => 'irc', 'nntp']);
+        $this->assertSame(['http', 'irc', 'nntp'], $field->getAllowedProtocols());
+
+        // Can reset back to config defaults
+        $field->setAllowedProtocols([]);
+        $this->assertSame(['ftp'], $field->getAllowedProtocols());
+    }
 }

tests/php/ORM/DBBooleanTest.php

@@ -0,0 +1,98 @@
+<?php
+
+namespace SilverStripe\ORM\Tests;
+
+use SilverStripe\Dev\SapphireTest;
+use PHPUnit\Framework\Attributes\DataProvider;
+use SilverStripe\ORM\FieldType\DBBoolean;
+
+class DBBooleanTest extends SapphireTest
+{
+    public function testDefaultValue(): void
+    {
+        $field = new DBBoolean('MyField');
+        $this->assertSame(false, $field->getValue());
+    }
+
+    public static function provideSetValue(): array
+    {
+        return [
+            'true' => [
+                'value' => true,
+                'expected' => true,
+            ],
+            'false' => [
+                'value' => false,
+                'expected' => false,
+            ],
+            '1-int' => [
+                'value' => 1,
+                'expected' => true,
+            ],
+            '1-string' => [
+                'value' => '1',
+                'expected' => true,
+            ],
+            '0-int' => [
+                'value' => 0,
+                'expected' => false,
+            ],
+            '0-string' => [
+                'value' => '0',
+                'expected' => false,
+            ],
+            't' => [
+                'value' => 't',
+                'expected' => true,
+            ],
+            'f' => [
+                'value' => 'f',
+                'expected' => false,
+            ],
+            'T' => [
+                'value' => 'T',
+                'expected' => true,
+            ],
+            'F' => [
+                'value' => 'F',
+                'expected' => false,
+            ],
+            'true-string' => [
+                'value' => 'true',
+                'expected' => true,
+            ],
+            'false-string' => [
+                'value' => 'false',
+                'expected' => false,
+            ],
+            '2-int' => [
+                'value' => 2,
+                'expected' => 2,
+            ],
+            '0.0' => [
+                'value' => 0.0,
+                'expected' => 0.0,
+            ],
+            '1.0' => [
+                'value' => 1.0,
+                'expected' => 1.0,
+            ],
+            'null' => [
+                'value' => null,
+                'expected' => null,
+            ],
+            'array' => [
+                'value' => [],
+                'expected' => [],
+            ],
+        ];
+    }
+
+    #[DataProvider('provideSetValue')]
+    public function testSetValue(mixed $value, mixed $expected): void
+    {
+        $field = new DBBoolean('MyField');
+        $field->setValue($value);
+        $this->assertSame($expected, $field->getValue());
+    }
+}

tests/php/ORM/DBCompositeTest.php

@@ -6,6 +6,9 @@ use SilverStripe\ORM\FieldType\DBMoney;
 use SilverStripe\ORM\DataObject;
 use SilverStripe\Dev\SapphireTest;
 use InvalidArgumentException;
+use PHPUnit\Framework\Attributes\DataProvider;
+use SilverStripe\ORM\FieldType\DBVarchar;
+use SilverStripe\ORM\FieldType\DBDecimal;
 
 class DBCompositeTest extends SapphireTest
 {
@@ -140,4 +143,12 @@ class DBCompositeTest extends SapphireTest
         // $this->assertSame($moneyField, $obj->dbObject('DoubleMoney'));
         // $this->assertEquals(20, $obj->dbObject('DoubleMoney')->getAmount());
     }
+
+    public function testGetValueForValidation(): void
+    {
+        $obj = DBCompositeTest\DBDoubleMoney::create();
+        $expected = [DBVarchar::class, DBDecimal::class];
+        $actual = array_map('get_class', $obj->getValueForValidation());
+        $this->assertSame($expected, $actual);
+    }
 }

tests/php/ORM/DBDateTest.php

@@ -10,6 +10,7 @@ use SilverStripe\ORM\FieldType\DBDate;
 use SilverStripe\ORM\FieldType\DBDatetime;
 use SilverStripe\ORM\FieldType\DBField;
 use PHPUnit\Framework\Attributes\DataProvider;
+use SilverStripe\Core\Validation\ValidationException;
 
 class DBDateTest extends SapphireTest
 {
@@ -91,20 +92,6 @@ class DBDateTest extends SapphireTest
         );
     }
 
-    public function testMDYConversion()
-    {
-        $this->expectException(InvalidArgumentException::class);
-        $this->expectExceptionMessage("Invalid date: '3/16/2003'. Use y-MM-dd to prevent this error.");
-        DBField::create_field('Date', '3/16/2003');
-    }
-
-    public function testY2kCorrection()
-    {
-        $this->expectException(InvalidArgumentException::class);
-        $this->expectExceptionMessage("Invalid date: '03-03-04'. Use y-MM-dd to prevent this error.");
-        DBField::create_field('Date', '03-03-04');
-    }
-
     public function testInvertedYearCorrection()
     {
         // iso8601 expects year first, but support year last
@@ -194,31 +181,57 @@ class DBDateTest extends SapphireTest
         );
     }
 
-    public function testSetNullAndZeroValues()
+    public static function provideSetNullAndZeroValues()
     {
-        $date = DBField::create_field('Date', '');
-        $this->assertNull($date->getValue(), 'Empty string evaluates to NULL');
+        return [
+            'blank-string' => [
+                'value' => '',
+                'expected' => ''
+            ],
+            'null' => [
+                'value' => null,
+                'expected' => null
+            ],
+            'false' => [
+                'value' => false,
+                'expected' => false
+            ],
+            'empty-array' => [
+                'value' => [],
+                'expected' => []
+            ],
+            'zero-string' => [
+                'value' => '0',
+                'expected' => '1970-01-01'
+            ],
+            'zero-int' => [
+                'value' => 0,
+                'expected' => '1970-01-01'
+            ],
+            'zero-datetime' => [
+                'value' => '0000-00-00 00:00:00',
+                'expected' => '0000-00-00 00:00:00'
+            ],
+            'zero-date-slashes' => [
+                'value' => '00/00/0000',
+                'expected' => '00/00/0000'
+            ],
+            'wrong-format-a' => [
+                'value' => '3/16/2003',
+                'expected' => '3/16/2003',
+            ],
+            'wrong-format-b' => [
+                'value' => '03-03-04',
+                'expected' => '2003-03-04',
+            ],
+        ];
+    }
 
-        $date = DBField::create_field('Date', null);
-        $this->assertNull($date->getValue(), 'NULL is set as NULL');
-
-        $date = DBField::create_field('Date', false);
-        $this->assertNull($date->getValue(), 'Boolean FALSE evaluates to NULL');
-
-        $date = DBField::create_field('Date', []);
-        $this->assertNull($date->getValue(), 'Empty array evaluates to NULL');
-
-        $date = DBField::create_field('Date', '0');
-        $this->assertEquals('1970-01-01', $date->getValue(), 'Zero is UNIX epoch date');
-
-        $date = DBField::create_field('Date', 0);
-        $this->assertEquals('1970-01-01', $date->getValue(), 'Zero is UNIX epoch date');
-
-        $date = DBField::create_field('Date', '0000-00-00 00:00:00');
-        $this->assertNull($date->getValue(), '0000-00-00 00:00:00 is set as NULL');
-
-        $date = DBField::create_field('Date', '00/00/0000');
-        $this->assertNull($date->getValue(), '00/00/0000 is set as NULL');
+    #[DataProvider('provideSetNullAndZeroValues')]
+    public function testSetNullAndZeroValues(mixed $value, mixed $expected)
+    {
+        $date = DBField::create_field('Date', $value);
+        $this->assertSame($expected, $date->getValue());
     }
 
     public function testDayOfMonth()

tests/php/ORM/DBDecimalTest.php

@@ -0,0 +1,87 @@
+<?php
+
+namespace SilverStripe\ORM\Tests;
+
+use SilverStripe\Dev\SapphireTest;
+use SilverStripe\ORM\FieldType\DBInt;
+use PHPUnit\Framework\Attributes\DataProvider;
+use SilverStripe\ORM\FieldType\DBDecimal;
+
+class DBDecimalTest extends SapphireTest
+{
+    public function testDefaultValue(): void
+    {
+        $field = new DBDecimal('MyField');
+        $this->assertSame(0.0, $field->getValue());
+    }
+
+    public static function provideSetValue(): array
+    {
+        return [
+            'float' => [
+                'value' => 9.123,
+                'expected' => 9.123,
+            ],
+            'negative-float' => [
+                'value' => -9.123,
+                'expected' => -9.123,
+            ],
+            'string-float' => [
+                'value' => '9.123',
+                'expected' => 9.123,
+            ],
+            'string-negative-float' => [
+                'value' => '-9.123',
+                'expected' => -9.123,
+            ],
+            'zero' => [
+                'value' => 0,
+                'expected' => 0.0,
+            ],
+            'int' => [
+                'value' => 3,
+                'expected' => 3.0,
+            ],
+            'negative-int' => [
+                'value' => -3,
+                'expected' => -3.0,
+            ],
+            'string-int' => [
+                'value' => '3',
+                'expected' => 3.0,
+            ],
+            'negative-string-int' => [
+                'value' => '-3',
+                'expected' => -3.0,
+            ],
+            'string' => [
+                'value' => 'fish',
+                'expected' => 'fish',
+            ],
+            'array' => [
+                'value' => [],
+                'expected' => [],
+            ],
+            'null' => [
+                'value' => null,
+                'expected' => null,
+            ],
+            'true' => [
+                'value' => true,
+                'expected' => true,
+            ],
+            'false' => [
+                'value' => false,
+                'expected' => false,
+            ],
+        ];
+    }
+
+    #[DataProvider('provideSetValue')]
+    public function testSetValue(mixed $value, mixed $expected): void
+    {
+        $field = new DBDecimal('MyField');
+        $field->setValue($value);
+        $this->assertSame($expected, $field->getValue());
+    }
+}

tests/php/ORM/DBEnumTest.php

@@ -118,7 +118,7 @@ class DBEnumTest extends SapphireTest
 
         $obj2 = new FieldType\DBEnumTestObject();
         $obj2->Colour = 'Purple';
-        $obj2->write();
+        $obj2->write(skipValidation: true);
 
         $this->assertEquals(
             ['Purple', 'Red'],
@@ -141,4 +141,38 @@ class DBEnumTest extends SapphireTest
             $colourField->getEnumObsolete()
         );
     }
+
+    public static function provideSetValue(): array
+    {
+        return [
+            'string' => [
+                'value' => 'green',
+                'expected' => 'green',
+            ],
+            'string-not-in-set' => [
+                'value' => 'purple',
+                'expected' => 'purple',
+            ],
+            'int' => [
+                'value' => 123,
+                'expected' => 123,
+            ],
+            'empty-string' => [
+                'value' => '',
+                'expected' => 'blue',
+            ],
+            'null' => [
+                'value' => null,
+                'expected' => 'blue',
+            ],
+        ];
+    }
+
+    #[DataProvider('provideSetValue')]
+    public function testSetValue(mixed $value, mixed $expected): void
+    {
+        $field = new DBEnum('TestField', ['red', 'green', 'blue'], 'blue');
+        $field->setValue($value);
+        $this->assertSame($expected, $field->getValue());
+    }
 }

tests/php/ORM/DBFieldTest.php

@@ -2,6 +2,7 @@
 
 namespace SilverStripe\ORM\Tests;
 
+use Exception;
 use SilverStripe\Assets\Image;
 use SilverStripe\ORM\FieldType\DBBigInt;
 use SilverStripe\ORM\FieldType\DBBoolean;
@@ -30,6 +31,33 @@ use SilverStripe\Dev\SapphireTest;
 use SilverStripe\ORM\FieldType\DBField;
 use SilverStripe\ORM\FieldType\DBYear;
 use PHPUnit\Framework\Attributes\DataProvider;
+use SilverStripe\Core\ClassInfo;
+use ReflectionClass;
+use SilverStripe\Core\Validation\FieldValidation\BooleanFieldValidator;
+use SilverStripe\Dev\TestOnly;
+use SilverStripe\Core\Validation\FieldValidation\BigIntFieldValidator;
+use SilverStripe\ORM\FieldType\DBClassName;
+use ReflectionMethod;
+use SilverStripe\Core\Validation\FieldValidation\CompositeFieldValidator;
+use SilverStripe\Core\Validation\FieldValidation\DateFieldValidator;
+use SilverStripe\Core\Validation\FieldValidation\DecimalFieldValidator;
+use SilverStripe\Core\Validation\FieldValidation\EmailFieldValidator;
+use SilverStripe\Core\Validation\FieldValidation\EnumFieldValidator;
+use SilverStripe\Core\Validation\FieldValidation\IntFieldValidator;
+use SilverStripe\Core\Validation\FieldValidation\IpFieldValidator;
+use SilverStripe\Core\Validation\FieldValidation\LocaleFieldValidator;
+use SilverStripe\Core\Validation\FieldValidation\MultiEnumFieldValidator;
+use SilverStripe\Core\Validation\FieldValidation\StringFieldValidator;
+use SilverStripe\Core\Validation\FieldValidation\TimeFieldValidator;
+use SilverStripe\Core\Validation\FieldValidation\UrlFieldValidator;
+use SilverStripe\Core\Validation\FieldValidation\YearFieldValidator;
+use SilverStripe\ORM\FieldType\DBUrl;
+use SilverStripe\ORM\FieldType\DBPolymorphicRelationAwareForeignKey;
+use SilverStripe\ORM\FieldType\DBIp;
+use SilverStripe\ORM\FieldType\DBEmail;
+use SilverStripe\Core\Validation\FieldValidation\DatetimeFieldValidator;
+use SilverStripe\Assets\Storage\DBFile;
+use SilverStripe\ORM\FieldType\DBClassNameVarchar;
 
 /**
  * Tests for DBField objects.
@@ -392,4 +420,154 @@ class DBFieldTest extends SapphireTest
 
         $this->assertEquals('new value', $obj->getField('MyTestField'));
     }
+
+    public function testDefaultValues(): void
+    {
+        $expectedBaseDefault = null;
+        $expectedDefaults = [
+            DBBoolean::class => 0,
+            DBDecimal::class => 0.0,
+            DBInt::class => 0,
+            DBFloat::class => 0.0,
+        ];
+        $classes = ClassInfo::subclassesFor(DBField::class);
+        foreach ($classes as $class) {
+            if (is_a($class, TestOnly::class, true)) {
+                continue;
+            }
+            $reflector = new ReflectionClass($class);
+            if ($reflector->isAbstract()) {
+                continue;
+            }
+            $expected = $expectedBaseDefault;
+            foreach ($expectedDefaults as $baseClass => $default) {
+                if ($class === $baseClass || is_subclass_of($class, $baseClass)) {
+                    $expected = $default;
+                    break;
+                }
+            }
+            $field = new $class('TestField');
+            $this->assertSame($expected, $field->getValue(), $class);
+        }
+    }
+
+    public function testFieldValidatorConfig(): void
+    {
+        $expectedFieldValidators = [
+            DBBigInt::class => [
+                BigIntFieldValidator::class,
+            ],
+            DBBoolean::class => [
+                BooleanFieldValidator::class,
+            ],
+            DBClassName::class => [
+                StringFieldValidator::class,
+                EnumFieldValidator::class,
+            ],
+            DBClassNameVarchar::class => [
+                StringFieldValidator::class,
+                EnumFieldValidator::class,
+            ],
+            DBCurrency::class => [
+                DecimalFieldValidator::class,
+            ],
+            DBDate::class => [
+                DateFieldValidator::class,
+            ],
+            DBDatetime::class => [
+                DatetimeFieldValidator::class,
+            ],
+            DBDecimal::class => [
+                DecimalFieldValidator::class,
+            ],
+            DBDouble::class => [],
+            DBEmail::class => [
+                StringFieldValidator::class,
+                EmailFieldValidator::class,
+            ],
+            DBEnum::class => [
+                StringFieldValidator::class,
+                EnumFieldValidator::class,
+            ],
+            DBFloat::class => [],
+            DBForeignKey::class => [
+                IntFieldValidator::class,
+            ],
+            DBHTMLText::class => [
+                StringFieldValidator::class,
+            ],
+            DBHTMLVarchar::class => [
+                StringFieldValidator::class,
+            ],
+            DBInt::class => [
+                IntFieldValidator::class,
+            ],
+            DBIp::class => [
+                StringFieldValidator::class,
+                IpFieldValidator::class,
+            ],
+            DBLocale::class => [
+                StringFieldValidator::class,
+                LocaleFieldValidator::class,
+            ],
+            DBMoney::class => [
+                CompositeFieldValidator::class,
+            ],
+            DBMultiEnum::class => [
+                StringFieldValidator::class,
+                MultiEnumFieldValidator::class,
+            ],
+            DBPercentage::class => [
+                DecimalFieldValidator::class,
+            ],
+            DBPolymorphicForeignKey::class => [],
+            DBPolymorphicRelationAwareForeignKey::class => [],
+            DBPrimaryKey::class => [
+                IntFieldValidator::class,
+            ],
+            DBText::class => [
+                StringFieldValidator::class,
+            ],
+            DBTime::class => [
+                TimeFieldValidator::class,
+            ],
+            DBUrl::class => [
+                StringFieldValidator::class,
+                UrlFieldValidator::class,
+            ],
+            DBVarchar::class => [
+                StringFieldValidator::class,
+            ],
+            DBYear::class => [
+                YearFieldValidator::class,
+            ],
+        ];
+        $count = 0;
+        $classes = ClassInfo::subclassesFor(DBField::class);
+        foreach ($classes as $class) {
+            if (is_a($class, TestOnly::class, true)) {
+                continue;
+            }
+            if (!str_starts_with($class, 'SilverStripe\ORM\FieldType')) {
+                continue;
+            }
+            $reflector = new ReflectionClass($class);
+            if ($reflector->isAbstract()) {
+                continue;
+            }
+            if (!array_key_exists($class, $expectedFieldValidators)) {
+                throw new Exception("No field validator config found for $class");
+            }
+            $expected = $expectedFieldValidators[$class];
+            $method = new ReflectionMethod($class, 'getFieldValidators');
+            $method->setAccessible(true);
+            $obj = new $class('MyField');
+            $actual = array_map('get_class', $method->invoke($obj));
+            $this->assertSame($expected, $actual, $class);
+            $count++;
+        }
+        // Assert that we have tested all classes e.g. namespace wasn't changed, no new classes were added
+        // that haven't been tested
+        $this->assertSame(29, $count);
+    }
 }

tests/php/ORM/DBForiegnKeyTest.php

@@ -0,0 +1,44 @@
+<?php
+
+namespace SilverStripe\ORM\Tests;
+
+use SilverStripe\Dev\SapphireTest;
+use PHPUnit\Framework\Attributes\DataProvider;
+use SilverStripe\ORM\FieldType\DBForeignKey;
+
+class DBForiegnKeyTest extends SapphireTest
+{
+    public static function provideSetValue(): array
+    {
+        return [
+            'int' => [
+                'value' => 2,
+                'expected' => 2,
+            ],
+            'string' => [
+                'value' => '2',
+                'expected' => '2',
+            ],
+            'zero' => [
+                'value' => 0,
+                'expected' => 0,
+            ],
+            'blank-string' => [
+                'value' => '',
+                'expected' => 0,
+            ],
+            'null' => [
+                'value' => null,
+                'expected' => null,
+            ],
+        ];
+    }
+
+    #[DataProvider('provideSetValue')]
+    public function testSetValue(mixed $value, mixed $expected): void
+    {
+        $field = new DBForeignKey('TestField');
+        $field->setValue($value);
+        $this->assertSame($expected, $field->getValue());
+    }
+}

tests/php/ORM/DBIntTest.php

@@ -4,15 +4,82 @@ namespace SilverStripe\ORM\Tests;
 
 use SilverStripe\Dev\SapphireTest;
 use SilverStripe\ORM\FieldType\DBInt;
+use PHPUnit\Framework\Attributes\DataProvider;
 
 class DBIntTest extends SapphireTest
 {
-    public function testGetValueCastToInt()
+    public function testDefaultValue(): void
     {
-        $field = DBInt::create('MyField');
-        $field->setValue(3);
-        $this->assertSame(3, $field->getValue());
-        $field->setValue('3');
-        $this->assertSame(3, $field->getValue());
+        $field = new DBInt('MyField');
+        $this->assertSame(0, $field->getValue());
+    }
+
+    public static function provideSetValue(): array
+    {
+        return [
+            'int' => [
+                'value' => 3,
+                'expected' => 3,
+            ],
+            'string-int' => [
+                'value' => '3',
+                'expected' => 3,
+            ],
+            'negative-int' => [
+                'value' => -3,
+                'expected' => -3,
+            ],
+            'negative-string-int' => [
+                'value' => '-3',
+                'expected' => -3,
+            ],
+            'float' => [
+                'value' => 3.5,
+                'expected' => 3.5,
+            ],
+            'string' => [
+                'value' => 'fish',
+                'expected' => 'fish',
+            ],
+            'array' => [
+                'value' => [],
+                'expected' => [],
+            ],
+            'null' => [
+                'value' => null,
+                'expected' => null,
+            ],
+        ];
+    }
+
+    #[DataProvider('provideSetValue')]
+    public function testSetValue(mixed $value, mixed $expected): void
+    {
+        $field = new DBInt('MyField');
+        $field->setValue($value);
+        $this->assertSame($expected, $field->getValue());
+    }
+
+    public static function provideValidate(): array
+    {
+        return [
+            'valid' => [
+                'value' => 123,
+                'expected' => true,
+            ],
+            'invalid' => [
+                'value' => 'abc',
+                'expected' => false,
+            ],
+        ];
+    }
+
+    #[DataProvider('provideValidate')]
+    public function testValidate(mixed $value, bool $expected): void
+    {
+        $field = new DBInt('MyField');
+        $field->setValue($value);
+        $result = $field->validate();
+        $this->assertSame($expected, $result->isValid());
     }
 }

tests/php/ORM/DBMultiEnumTest.php

@@ -0,0 +1,44 @@
+<?php
+
+namespace SilverStripe\ORM\Tests;
+
+use SilverStripe\Dev\SapphireTest;
+use SilverStripe\ORM\FieldType\DBMultiEnum;
+use PHPUnit\Framework\Attributes\DataProvider;
+
+class DBMultiEnumTest extends SapphireTest
+{
+    public static function provideGetValueForValidation(): array
+    {
+        return [
+            'array' => [
+                'value' => ['Red', 'Green'],
+                'expected' => ['Red', 'Green'],
+            ],
+            'string' => [
+                'value' => 'Red,Green',
+                'expected' => ['Red', 'Green'],
+            ],
+            'string-non-existant-value' => [
+                'value' => 'Red,Green,Purple',
+                'expected' => ['Red', 'Green', 'Purple'],
+            ],
+            'empty-string' => [
+                'value' => '',
+                'expected' => [''],
+            ],
+            'null' => [
+                'value' => null,
+                'expected' => [''],
+            ],
+        ];
+    }
+
+    #[DataProvider('provideGetValueForValidation')]
+    public function testGetValueForValidation(mixed $value, array $expected): void
+    {
+        $obj = new DBMultiEnum('TestField', ['Red', 'Green', 'Blue']);
+        $obj->setValue($value);
+        $this->assertSame($expected, $obj->getValueForValidation());
+    }
+}

tests/php/ORM/DBReplicaTest.php

@@ -0,0 +1,260 @@
+<?php
+
+namespace SilverStripe\ORM\Tests;
+
+use ReflectionClass;
+use SilverStripe\Dev\FunctionalTest;
+use SilverStripe\ORM\DB;
+use SilverStripe\Control\Director;
+use SilverStripe\Security\Security;
+use SilverStripe\Core\Config\Config;
+use SilverStripe\ORM\Tests\DBReplicaTest\TestController;
+use SilverStripe\ORM\Tests\DBReplicaTest\TestObject;
+use SilverStripe\Security\Group;
+use SilverStripe\Security\Member;
+use SilverStripe\ORM\DataQuery;
+use PHPUnit\Framework\Attributes\DataProvider;
+
+class DBReplicaTest extends FunctionalTest
+{
+    protected static $extra_dataobjects = [
+        TestObject::class,
+    ];
+
+    protected static $fixture_file = 'DBReplicaTest.yml';
+
+    protected function setUp(): void
+    {
+        parent::setUp();
+        $this->setupConfigsAndConnections(true);
+        // Set DB:$mustUsePrimary to true to allow using replicas
+        // This is disabled by default in SapphireTest::setUpBeforeClass()
+        // Also reset mustUsePrimary after using mutable sql to create yml fixtures
+        // and also because by default an ADMIN user is logged in when using fixtures in SapphireTest::setUp()
+        // and also prevent tests from affecting subsequent tests
+        (new ReflectionClass(DB::class))->setStaticPropertyValue('mustUsePrimary', false);
+    }
+
+    protected function tearDown(): void
+    {
+        $this->setupConfigsAndConnections(false);
+        // Reset DB:$mustUsePrimary to true which is the default set by SapphireTest::setUpBeforeClass()
+        (new ReflectionClass(DB::class))->setStaticPropertyValue('mustUsePrimary', true);
+        parent::tearDown();
+    }
+    
+    public function testUsesReplica(): void
+    {
+        // Assert uses replica by default
+        TestObject::get()->count();
+        $this->assertSame('replica_01', $this->getLastConnectionName());
+        // Assert uses primary when using withPrimary()
+        DB::withPrimary(fn() => TestObject::get()->count());
+        $this->assertSame(DB::CONN_PRIMARY, $this->getLastConnectionName());
+        // Assert that withPrimary() was only temporary
+        TestObject::get()->count();
+        $this->assertSame('replica_01', $this->getLastConnectionName());
+        // Assert DB::setMustUsePrimary() forces primary from now on
+        DB::setMustUsePrimary();
+        TestObject::get()->count();
+        $this->assertSame(DB::CONN_PRIMARY, $this->getLastConnectionName());
+    }
+
+    public function testMutableSql(): void
+    {
+        // Assert that using mutable sql in an ORM method with a dataclass uses primary
+        TestObject::create(['Title' => 'testing'])->write();
+        $this->assertSame(DB::CONN_PRIMARY, $this->getLastConnectionName());
+        // Assert that now all subsequent queries use primary
+        TestObject::get()->count();
+        $this->assertSame(DB::CONN_PRIMARY, $this->getLastConnectionName());
+    }
+
+    public function testMutableSqlDbQuery(): void
+    {
+        // Assert that using mutable sql in DB::query() uses primary
+        DB::query('INSERT INTO "DBReplicaTest_TestObject" ("Title") VALUES (\'testing\')');
+        $this->assertSame(DB::CONN_PRIMARY, $this->getLastConnectionName());
+        // Assert that now all subsequent queries use primary
+        TestObject::get()->count();
+        $this->assertSame(DB::CONN_PRIMARY, $this->getLastConnectionName());
+    }
+
+    public function testMutableSqlDbPreparedQuery(): void
+    {
+        // Assert that using mutable sql in DB::prepared_query() uses primary
+        DB::prepared_query('INSERT INTO "DBReplicaTest_TestObject" ("Title") VALUES (?)', ['testing']);
+        $this->assertSame(DB::CONN_PRIMARY, $this->getLastConnectionName());
+        // Assert that now all subsequent queries use primary
+        TestObject::get()->count();
+        $this->assertSame(DB::CONN_PRIMARY, $this->getLastConnectionName());
+    }
+
+    #[DataProvider('provideSetCurrentUser')]
+    public function testSetCurrentUser(string $firstName, string $expected): void
+    {
+        $member = Member::get()->find('FirstName', $firstName);
+        Security::setCurrentUser($member);
+        TestObject::get()->count();
+        $this->assertSame($expected, $this->getLastConnectionName());
+    }
+
+    public function testDataObjectMustUsePrimaryDb(): void
+    {
+        // Assert that DataList::getIterator() respect DataObject.must_use_primary_db
+        foreach (TestObject::get() as $object) {
+            $object->Title = 'test2';
+        }
+        $this->assertSame('replica_01', $this->getLastConnectionName());
+        foreach (Group::get() as $group) {
+            $group->Title = 'test2';
+        }
+        $this->assertSame(DB::CONN_PRIMARY, $this->getLastConnectionName());
+        // Assert that DataQuery methods without params respect DataObject.must_use_primary_db
+        $methods = [
+            'count',
+            'exists',
+            'firstRow',
+            'lastRow'
+        ];
+        foreach ($methods as $method) {
+            (new DataQuery(TestObject::class))->$method();
+            $this->assertSame('replica_01', $this->getLastConnectionName(), "method is $method");
+            (new DataQuery(Group::class))->$method();
+            $this->assertSame(DB::CONN_PRIMARY, $this->getLastConnectionName(), "method is $method");
+        }
+        // Assert that DataQuery methods with a param respect DataObject.must_use_primary_db
+        $methods = [
+            'max',
+            'min',
+            'avg',
+            'sum',
+            'column',
+        ];
+        foreach ($methods as $method) {
+            (new DataQuery(TestObject::class))->$method('ID');
+            $this->assertSame('replica_01', $this->getLastConnectionName(), "method is $method");
+            (new DataQuery(Group::class))->$method('ID');
+            $this->assertSame(DB::CONN_PRIMARY, $this->getLastConnectionName(), "method is $method");
+        }
+    }
+
+    public static function provideSetCurrentUser(): array
+    {
+        return [
+            'non_cms_user' => [
+                'firstName' => 'random',
+                'expected' => 'replica_01'
+            ],
+            'cms_user' => [
+                'firstName' => 'cmsuser',
+                'expected' => DB::CONN_PRIMARY
+            ],
+        ];
+    }
+
+    public static function provideRoutes(): array
+    {
+        return [
+            'normal_route' => [
+                'path' => 'test',
+                'expected' => 'replica_01'
+            ],
+            'security_route' => [
+                'path' => 'Security/login',
+                'expected' => DB::CONN_PRIMARY
+            ],
+            'dev_route' => [
+                'path' => 'dev/tasks',
+                'expected' => DB::CONN_PRIMARY
+            ],
+            'dev_in_path_but_not_dev_route' => [
+                'path' => 'test/dev',
+                'expected' => 'replica_01'
+            ],
+        ];
+    }
+
+    #[DataProvider('provideRoutes')]
+    public function testRoutes(string $path, string $expected): void
+    {
+        // Create a custom rule to test our controller that should default to using a replica
+        $rules = Config::inst()->get(Director::class, 'rules');
+        $rules['test'] = TestController::class;
+        // Ensure that routes staring with '$' are at the bottom of the assoc array index and don't override
+        // our new 'test' route
+        uksort($rules, fn($a, $b) => str_starts_with($a, '$') ? 1 : (str_starts_with($b, '$') ? -1 : 0));
+        $this->get($path);
+        $this->assertSame($expected, $this->getLastConnectionName());
+    }
+
+    public static function provideHasReplicaConfig(): array
+    {
+        return [
+            'no_replica' => [
+                'includeReplica' => false,
+                'expected' => false
+            ],
+            'with_replica' => [
+                'includeReplica' => true,
+                'expected' => true
+            ],
+        ];
+    }
+
+    #[DataProvider('provideHasReplicaConfig')]
+    public function testHasReplicaConfig(bool $includeReplica, bool $expected): void
+    {
+        $this->assertTrue(DB::hasReplicaConfig());
+        $primaryConfig = DB::getConfig(DB::CONN_PRIMARY);
+        $config = [DB::CONN_PRIMARY => $primaryConfig];
+        if ($includeReplica) {
+            $config['replica_01'] = $primaryConfig;
+        }
+        (new ReflectionClass(DB::class))->setStaticPropertyValue('configs', $config);
+        $this->assertSame($expected, DB::hasReplicaConfig());
+    }
+
+    public function testHasConfig(): void
+    {
+        $this->assertFalse(DB::hasConfig('lorem'));
+        DB::setConfig(['type' => 'lorem'], 'lorem');
+        $this->assertTrue(DB::hasConfig('lorem'));
+    }
+
+    public function testGetReplicaConfigKey(): void
+    {
+        $this->assertSame('replica_03', DB::getReplicaConfigKey(3));
+        $this->assertSame('replica_58', DB::getReplicaConfigKey(58));
+    }
+
+    /**
+     * Using reflection, set DB::configs and DB::connections with a fake a replica connection
+     * that points to the same connection as the primary connection.
+     */
+    private function setupConfigsAndConnections($includeReplica = true): void
+    {
+        $reflector = new ReflectionClass(DB::class);
+        $primaryConfig = DB::getConfig(DB::CONN_PRIMARY);
+        $configs = [DB::CONN_PRIMARY => $primaryConfig];
+        if ($includeReplica) {
+            $configs['replica_01'] = $primaryConfig;
+        }
+        $reflector->setStaticPropertyValue('configs', $configs);
+        // Create connections
+        $primaryConnection = DB::get_conn(DB::CONN_PRIMARY);
+        $connections = [DB::CONN_PRIMARY => $primaryConnection];
+        if ($includeReplica) {
+            $connections['replica_01'] = $primaryConnection;
+        }
+        $reflector->setStaticPropertyValue('connections', $connections);
+    }
+
+    /**
+     * Get the last connection name used by the DB class. This shows if a replica was used.
+     */
+    private function getLastConnectionName(): string
+    {
+        return (new ReflectionClass(DB::class))->getStaticPropertyValue('lastConnectionName');
+    }
+}

tests/php/ORM/DBReplicaTest.yml

@@ -0,0 +1,18 @@
+SilverStripe\ORM\Tests\DBReplicaTest\TestObject:
+  test:
+    Title: 'test'
+SilverStripe\Security\Permission:
+  test:
+    Code: 'CMS_ACCESS_Something'
+SilverStripe\Security\Group:
+  test:
+    Title: 'test'
+    Permissions:
+      - =>SilverStripe\Security\Permission.test
+SilverStripe\Security\Member:
+  cmsuser:
+    FirstName: 'CmsUser'
+    Groups:
+      - =>SilverStripe\Security\Group.test
+  random:
+    FirstName: 'Random'

tests/php/ORM/DBReplicaTest/TestController.php

@@ -0,0 +1,18 @@
+<?php
+
+namespace SilverStripe\ORM\Tests\DBReplicaTest;
+
+use SilverStripe\Control\Controller;
+use SilverStripe\Dev\TestOnly;
+
+class TestController extends Controller implements TestOnly
+{
+    public function index()
+    {
+        // Make a call to the database
+        TestObject::get()->count();
+        $response = $this->getResponse();
+        $response->setBody('DB_REPLICA_TEST_CONTROLLER');
+        return $response;
+    }
+}

tests/php/ORM/DBReplicaTest/TestObject.php

@@ -0,0 +1,16 @@
+<?php
+
+namespace SilverStripe\ORM\Tests\DBReplicaTest;
+
+use SilverStripe\Control\Controller;
+use SilverStripe\Dev\TestOnly;
+use SilverStripe\ORM\DataObject;
+
+class TestObject extends DataObject implements TestOnly
+{
+    private static $db = [
+        'Title' => 'Varchar',
+    ];
+
+    private static $table_name = 'DBReplicaTest_TestObject';
+}

tests/php/ORM/DBStringTest.php

@@ -7,6 +7,7 @@ use SilverStripe\ORM\FieldType\DBField;
 use SilverStripe\ORM\FieldType\DBString;
 use SilverStripe\Dev\SapphireTest;
 use SilverStripe\ORM\Tests\DBStringTest\MyStringField;
+use PHPUnit\Framework\Attributes\DataProvider;
 
 class DBStringTest extends SapphireTest
 {

tests/php/ORM/DBYearTest.php

@@ -5,6 +5,7 @@ namespace SilverStripe\ORM\Tests;
 use SilverStripe\Forms\DropdownField;
 use SilverStripe\ORM\FieldType\DBYear;
 use SilverStripe\Dev\SapphireTest;
+use PHPUnit\Framework\Attributes\DataProvider;
 
 class DBYearTest extends SapphireTest
 {
@@ -18,15 +19,15 @@ class DBYearTest extends SapphireTest
         $field = $year->scaffoldFormField("YearTest");
         $this->assertEquals(DropdownField::class, get_class($field));
 
-        //This should be a list of years from the current one, counting down to 1900
+        //This should be a list of years from the current one, counting down to 1901
         $source = $field->getSource();
 
         $lastValue = end($source);
         $lastKey = key($source ?? []);
 
-        //Keys and values should be the same - and the last one should be 1900
-        $this->assertEquals(1900, $lastValue);
-        $this->assertEquals(1900, $lastKey);
+        //Keys and values should be the same - and the last one should be 1901
+        $this->assertEquals(1901, $lastValue);
+        $this->assertEquals(1901, $lastKey);
     }
 
     public function testScaffoldFormFieldLast()
@@ -43,4 +44,98 @@ class DBYearTest extends SapphireTest
         $this->assertEquals($currentYear, $firstValue);
         $this->assertEquals($currentYear, $firstKey);
     }
+
+    public static function provideSetValue(): array
+    {
+        return [
+            '4-int' => [
+                'value' => 2024,
+                'expected' => 2024,
+            ],
+            '2-int' => [
+                'value' => 24,
+                'expected' => 2024,
+            ],
+            '0-int' => [
+                'value' => 0,
+                'expected' => 0,
+            ],
+            '4-string' => [
+                'value' => '2024',
+                'expected' => 2024,
+            ],
+            '2-string' => [
+                'value' => '24',
+                'expected' => 2024,
+            ],
+            '0-string' => [
+                'value' => '0',
+                'expected' => 0,
+            ],
+            '00-string' => [
+                'value' => '00',
+                'expected' => 2000,
+            ],
+            '0000-string' => [
+                'value' => '0000',
+                'expected' => 0,
+            ],
+            '4-int-low' => [
+                'value' => 1900,
+                'expected' => 1900,
+            ],
+            '4-int-low' => [
+                'value' => 2156,
+                'expected' => 2156,
+            ],
+            '4-string-low' => [
+                'value' => '1900',
+                'expected' => 1900,
+            ],
+            '4-string-low' => [
+                'value' => '2156',
+                'expected' => 2156,
+            ],
+            'int-negative' => [
+                'value' => -2024,
+                'expected' => -2024,
+            ],
+            'string-negative' => [
+                'value' => '-2024',
+                'expected' => '-2024',
+            ],
+            'float' => [
+                'value' => 2024.0,
+                'expected' => 2024.0,
+            ],
+            'string-float' => [
+                'value' => '2024.0',
+                'expected' => '2024.0',
+            ],
+            'null' => [
+                'value' => null,
+                'expected' => null,
+            ],
+            'true' => [
+                'value' => true,
+                'expected' => true,
+            ],
+            'false' => [
+                'value' => false,
+                'expected' => false,
+            ],
+            'array' => [
+                'value' => [],
+                'expected' => [],
+            ],
+        ];
+    }
+
+    #[DataProvider('provideSetValue')]
+    public function testSetValue(mixed $value, mixed $expected): void
+    {
+        $field = new DBYear('MyField');
+        $result = $field->setValue($value);
+        $this->assertSame($expected, $field->getValue());
+    }
 }

tests/php/ORM/MySQLiConnectorTest.php

@@ -41,7 +41,7 @@ class MySQLiConnectorTest extends SapphireTest implements TestOnly
     {
         parent::setUp();
 
-        $config = DB::getConfig();
+        $config = DB::getConfig(DB::CONN_PRIMARY);
 
         if (strtolower(substr($config['type'] ?? '', 0, 5)) !== 'mysql') {
             $this->markTestSkipped("The test only relevant for MySQL - but $config[type] is in use");