silverstripe-framework/docs/en/02_Developer_Guides/00_Model/03_DataObject.md

DataObject

Introduction

The [api:DataObject] class represents a single row in a database table, following the "Active Record" design pattern.

Defining Properties

Properties defined through DataObject::$db map to table columns, and can be declared as different data-types.

Loading and Saving Records

The basic principles around data persistence and querying for objects is explained in the "datamodel" topic.

Defining Form Fields

In addition to defining how data is persisted, the class can also help with editing it by providing form fields through DataObject->getCMSFields(). The resulting [api:FieldList] is the centrepiece of many data administration interfaces in SilverStripe. Many customizations of the SilverStripe CMS interface start here, by adding, removing or configuring fields.

Here is an example getCMSFields implementation:

:::php
class MyDataObject extends DataObject {
  $db = array(
  	'IsActive' => 'Boolean'
  );
  public function getCMSFields() {
    return new FieldList(
    	new CheckboxField('IsActive')
    );
  }
}

There's various form field types, for editing text, dates, restricting input to numbers, and much more.

Scaffolding Form Fields

The ORM already has a lot of information about the data represented by a DataObject through its $db property, so why not use it to create form fields as well? If you call the parent implementation, the class will use [api:FormScaffolder] to provide reasonable defaults based on the property type (e.g. a checkbox field for booleans). You can then further customize those fields as required.

:::php
class MyDataObject extends DataObject {
	// ...
  public function getCMSFields() {
    $fields = parent::getCMSFields();
    $fields->fieldByName('IsActive')->setTitle('Is active?');
    return $fields;
  }
}

The ModelAdmin class uses this approach to provide data management interfaces with very little custom coding.

You can also alter the fields of built-in and module DataObject classes through your own DataExtension, and a call to DataExtension->updateCMSFields(). [api::DataObject->beforeUpdateCMSFields()] can also be used to interact with and add to automatically scaffolded fields prior to being passed to extensions (See DataExtension).

Searchable Fields

The $searchable_fields property uses a mixed array format that can be used to further customize your generated admin system. The default is a set of array values listing the fields.

Example: Getting predefined searchable fields

:::php
$fields = singleton('MyDataObject')->searchableFields();

Example: Simple Definition

:::php
class MyDataObject extends DataObject {
   private static $searchable_fields = array(
      'Name',
      'ProductCode'
   );
}

Searchable fields will be appear in the search interface with a default form field (usually a [api:TextField]) and a default search filter assigned (usually an [api:ExactMatchFilter]). To override these defaults, you can specify additional information on $searchable_fields:

:::php
class MyDataObject extends DataObject {
   private static $searchable_fields = array(
       'Name' => 'PartialMatchFilter',
       'ProductCode' => 'NumericField'
   );
}

If you assign a single string value, you can set it to be either a [api:FormField] or [api:SearchFilter]. To specify both, you can assign an array:

:::php
class MyDataObject extends DataObject {
   private static $searchable_fields = array(
       'Name' => array(
          'field' => 'TextField',
          'filter' => 'PartialMatchFilter',
       ),
       'ProductCode' => array(
           'title' => 'Product code #',
           'field' => 'NumericField',
           'filter' => 'PartialMatchFilter',
       ),
   );
}

To include relations ($has_one, $has_many and $many_many) in your search, you can use a dot-notation.

:::php
class Team extends DataObject {
  private static $db = array(
    'Title' => 'Varchar'
  );
  private static $many_many = array(
    'Players' => 'Player'
  );
  private static $searchable_fields = array(
      'Title',
      'Players.Name',
   );
}
class Player extends DataObject {
  private static $db = array(
    'Name' => 'Varchar',
    'Birthday' => 'Date'
  );
  private static $belongs_many_many = array(
    'Teams' => 'Team'
  );
}

Summary Fields

Summary fields can be used to show a quick overview of the data for a specific [api:DataObject] record. Most common use is their display as table columns, e.g. in the search results of a [api:ModelAdmin] CMS interface.

Example: Getting predefined summary fields

:::php
$fields = singleton('MyDataObject')->summaryFields();

Example: Simple Definition

:::php
class MyDataObject extends DataObject {
  private static $db = array(
    'Name' => 'Text',
    'OtherProperty' => 'Text',
    'ProductCode' => 'Int',
  ); 
  private static $summary_fields = array(
    'Name',
    'ProductCode'
  );
}

To include relations or field manipulations in your summaries, you can use a dot-notation.

:::php
class OtherObject extends DataObject {
  private static $db = array(
    'Title' => 'Varchar'
  );
}
class MyDataObject extends DataObject {
  private static $db = array(
    'Name' => 'Text',
    'Description' => 'HTMLText'
  );
  private static $has_one = array(
    'OtherObject' => 'OtherObject'
  );
  private static $summary_fields = array(
    'Name' => 'Name',
    'Description.Summary' => 'Description (summary)',
    'OtherObject.Title' => 'Other Object Title'
  );
}

Non-textual elements (such as images and their manipulations) can also be used in summaries.

:::php
class MyDataObject extends DataObject {
  private static $db = array(
    'Name' => 'Text'
  );
  private static $has_one = array(
    'HeroImage' => 'Image'
  );
  private static $summary_fields = array(
    'Name' => 'Name',
    'HeroImage.CMSThumbnail' => 'Hero Image'
  );
}

Permissions

Models can be modified in a variety of controllers and user interfaces, all of which can implement their own security checks. But often it makes sense to centralize those checks on the model, regardless of the used controller.

The API provides four methods for this purpose: canEdit(), canCreate(), canView() and canDelete(). Since they're PHP methods, they can contain arbitrary logic matching your own requirements. They can optionally receive a $member argument, and default to the currently logged in member (through Member::currentUser()).

Example: Check for CMS access permissions

class MyDataObject extends DataObject {
  // ...
	public function canView($member = null) {
		return Permission::check('CMS_ACCESS_CMSMain', 'any', $member);
	}
	public function canEdit($member = null) {
		return Permission::check('CMS_ACCESS_CMSMain', 'any', $member);
	}
	public function canDelete($member = null) {
		return Permission::check('CMS_ACCESS_CMSMain', 'any', $member);
	}
	public function canCreate($member = null) {
		return Permission::check('CMS_ACCESS_CMSMain', 'any', $member);
	}
}

Important: These checks are not enforced on low-level ORM operations such as write() or delete(), but rather rely on being checked in the invoking code. The CMS default sections as well as custom interfaces like ModelAdmin or GridField already enforce these permissions.

Indexes

It is sometimes desirable to add indexes to your data model, whether to optimize queries or add a uniqueness constraint to a field. This is done through the DataObject::$indexes map, which maps index names to descriptor arrays that represent each index. There's several supported notations:

:::php
# Simple
private static $indexes = array(
	'<column-name>' => true
);

# Advanced
private static $indexes = array(
	'<index-name>' => array('type' => '<type>', 'value' => '"<column-name>"')
);

# SQL
private static $indexes = array(
	'<index-name>' => 'unique("<column-name>")'
);

The <index-name> can be an an arbitrary identifier in order to allow for more than one index on a specific database column. The "advanced" notation supports more <type> notations. These vary between database drivers, but all of them support the following:

• index: Standard index
• unique: Index plus uniqueness constraint on the value
• fulltext: Fulltext content index

In order to use more database specific or complex index notations, we also support raw SQL for as a value in the $indexes definition. Keep in mind this will likely make your code less portable between databases.

Example: A combined index on a two fields.

:::php
private static $db = array(
	'MyField' => 'Varchar',
	'MyOtherField' => 'Varchar',
);
private static $indexes = array(
	'MyIndexName' => array('type' => 'index', 'value' => '"MyField","MyOtherField"'),
);

API Documentation

[api:DataObject]