125 lines
3.0 KiB
PHP
125 lines
3.0 KiB
PHP
<?php
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namespace SilverStripe\ORM\Queries;
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use SilverStripe\Core\Convert;
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use SilverStripe\ORM\Connect\Query;
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use SilverStripe\ORM\DB;
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use Exception;
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/**
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* Abstract base class for an object representing an SQL query.
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* The various parts of the SQL query can be manipulated individually.
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*/
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abstract class SQLExpression {
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/**
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* Keep an internal register of find/replace pairs to execute when it's time to actually get the
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* query SQL.
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* @var array
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*/
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protected $replacementsOld = array();
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/**
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* Keep an internal register of find/replace pairs to execute when it's time to actually get the
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* query SQL.
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* @var array
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*/
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protected $replacementsNew = array();
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/**
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* Swap some text in the SQL query with another.
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*
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* Note that values in parameters will not be replaced
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*
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* @param string $old The old text (escaped)
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* @param string $new The new text (escaped)
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*/
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public function replaceText($old, $new) {
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$this->replacementsOld[] = $old;
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$this->replacementsNew[] = $new;
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}
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/**
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* Return the generated SQL string for this query
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*
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* @todo Is it ok for this to consider parameters? Test cases here!
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*
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* @return string
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*/
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public function __toString() {
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try {
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$sql = $this->sql($parameters);
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if(!empty($parameters)) {
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$sql .= " <" . var_export($parameters, true) . ">";
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}
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return $sql;
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} catch(Exception $e) {
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return "<sql query>";
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}
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}
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/**
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* Swap the use of one table with another.
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*
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* @param string $old Name of the old table (unquoted, escaped)
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* @param string $new Name of the new table (unquoted, escaped)
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*/
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public function renameTable($old, $new) {
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$this->replaceText("`$old`", "`$new`");
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$this->replaceText("\"$old\"", "\"$new\"");
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$this->replaceText(Convert::symbol2sql($old), Convert::symbol2sql($new));
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}
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/**
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* Determine if this query is empty, and thus cannot be executed
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*
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* @return bool Flag indicating that this query is empty
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*/
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abstract public function isEmpty();
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/**
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* Generate the SQL statement for this query.
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*
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* @param array $parameters Out variable for parameters required for this query
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* @return string The completed SQL query
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*/
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public function sql(&$parameters = array()) {
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// Build each component as needed
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$sql = DB::build_sql($this, $parameters);
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if(empty($sql)) return null;
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if($this->replacementsOld) {
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$sql = str_replace($this->replacementsOld, $this->replacementsNew, $sql);
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}
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return $sql;
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}
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/**
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* Execute this query.
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*
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* @return Query
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*/
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public function execute() {
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$sql = $this->sql($parameters);
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return DB::prepared_query($sql, $parameters);
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}
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/**
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* Copies the query parameters contained in this object to another
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* SQLExpression
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*
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* @param SQLExpression $object The object to copy properties to
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*/
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protected function copyTo(SQLExpression $object) {
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$target = array_keys(get_object_vars($object));
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foreach(get_object_vars($this) as $variable => $value) {
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if(in_array($variable, $target)) {
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$object->$variable = $value;
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}
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}
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}
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}
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