# Class yii\behaviors\AttributesBehavior

Inheritance | yii\behaviors\AttributesBehavior » yii\base\Behavior » yii\base\BaseObject
Implements | yii\base\Configurable
Available since version | 2.0.13
Source Code | https://github.com/yiisoft/yii2/blob/master/framework/behaviors/AttributesBehavior.php

AttributesBehavior automatically assigns values specified to one or multiple attributes of an ActiveRecord object when certain events happen.

To use AttributesBehavior, configure the $attributes property which should specify the list of attributes that need to be updated and the corresponding events that should trigger the update. Then configure the value of enclosed arrays with a PHP callable whose return value will be used to assign to the current attribute. For example,

    use yii\behaviors\AttributesBehavior;

    public function behaviors()
    {
        return [
            [
                'class' => AttributesBehavior::className(),
                'attributes' => [
                    'attribute1' => [
                        ActiveRecord::EVENT_BEFORE_INSERT => new Expression('NOW()'),
                        ActiveRecord::EVENT_BEFORE_UPDATE => \Yii::$app->formatter->asDatetime('2017-07-13'),
                    ],
                    'attribute2' => [
                        ActiveRecord::EVENT_BEFORE_VALIDATE => [$this, 'storeAttributes'],
                        ActiveRecord::EVENT_AFTER_VALIDATE => [$this, 'restoreAttributes'],
                    ],
                    'attribute3' => [
                        ActiveRecord::EVENT_BEFORE_VALIDATE => $fn2 = [$this, 'getAttribute2'],
                        ActiveRecord::EVENT_AFTER_VALIDATE => $fn2,
                    ],
                    'attribute4' => [
                        ActiveRecord::EVENT_BEFORE_DELETE => function ($event, $attribute) {
                            static::disabled() || $event->isValid = false;
                        },
                    ],
                ],
            ],
        ];
    }

Because attribute values will be set automatically by this behavior, they are usually not user input and should therefore not be validated, i.e. they should not appear in the rules() method of the model.

## Public Properties

Hide inherited properties

Property | Type | Description | Defined By
--- | --- | --- | ---
$attributes | array | List of attributes that are to be automatically filled with the values specified via enclosed arrays. | yii\behaviors\AttributesBehavior
$order | array | List of order of attributes that are to be automatically filled with the event. | yii\behaviors\AttributesBehavior
$owner | yii\base\Component|null | The owner of this behavior | yii\base\Behavior
$preserveNonEmptyValues | boolean | Whether to preserve non-empty attribute values. | yii\behaviors\AttributesBehavior
$skipUpdateOnClean | boolean | Whether to skip this behavior when the `$owner` has not been modified | yii\behaviors\AttributesBehavior

## Public Methods

Hide inherited methods

Method | Description | Defined By
--- | --- | ---
__call() | Calls the named method which is not a class method. | yii\base\BaseObject
__construct() | Constructor. | yii\base\BaseObject
__get() | Returns the value of an object property. | yii\base\BaseObject
__isset() | Checks if a property is set, i.e. defined and not null. | yii\base\BaseObject
__set() | Sets value of an object property. | yii\base\BaseObject
__unset() | Sets an object property to null. | yii\base\BaseObject
attach() | Attaches the behavior object to the component. | yii\base\Behavior
canGetProperty() | Returns a value indicating whether a property can be read. | yii\base\BaseObject
canSetProperty() | Returns a value indicating whether a property can be set. | yii\base\BaseObject
className() | Returns the fully qualified name of this class. | yii\base\BaseObject
detach() | Detaches the behavior object from the component. | yii\base\Behavior
evaluateAttributes() | Evaluates the attributes values and assigns it to the current attributes. | yii\behaviors\AttributesBehavior
events() | Declares event handlers for the $owner's events. | yii\behaviors\AttributesBehavior
hasMethod() | Returns a value indicating whether a method is defined. | yii\base\BaseObject
hasProperty() | Returns a value indicating whether a property is defined. | yii\base\BaseObject
init() | Initializes the object. | yii\base\BaseObject

## Protected Methods

Hide inherited methods

Method | Description | Defined By
--- | --- | ---
getValue() | Returns the value for the current attributes. | yii\behaviors\AttributesBehavior

## Property Details

$attributes public property

List of attributes that are to be automatically filled with the values specified via enclosed arrays. The array keys are the ActiveRecord attributes upon which the events are to be updated, and the array values are the array of corresponding events(s). For this enclosed array: the array keys are the ActiveRecord events upon which the attributes are to be updated, and the array values are the value that will be assigned to the current attributes. This can be an anonymous function, callable in array format (e.g. `[$this, 'methodName']`), an Expression object representing a DB expression (e.g. `new Expression('NOW()')`), scalar, string or an arbitrary value. If the former, the return value of the function will be assigned to the attributes.

    [
      'attribute1' => [
          ActiveRecord::EVENT_BEFORE_INSERT => new Expression('NOW()'),
          ActiveRecord::EVENT_BEFORE_UPDATE => \Yii::$app->formatter->asDatetime('2017-07-13'),
      ],
      'attribute2' => [
          ActiveRecord::EVENT_BEFORE_VALIDATE => [$this, 'storeAttributes'],
          ActiveRecord::EVENT_AFTER_VALIDATE => [$this, 'restoreAttributes'],
      ],
      'attribute3' => [
          ActiveRecord::EVENT_BEFORE_VALIDATE => $fn2 = [$this, 'getAttribute2'],
          ActiveRecord::EVENT_AFTER_VALIDATE => $fn2,
      ],
      'attribute4' => [
          ActiveRecord::EVENT_BEFORE_DELETE => function ($event, $attribute) {
              static::disabled() || $event->isValid = false;
          },
      ],
    ]

public array $attributes = []
$order public property

List of order of attributes that are to be automatically filled with the event. The array keys are the ActiveRecord events upon which the attributes are to be updated, and the array values are represent the order corresponding attributes. The rest of the attributes are processed at the end. If the $attributes for this attribute do not specify this event, it is ignored

    [
        ActiveRecord::EVENT_BEFORE_VALIDATE => ['attribute1', 'attribute2'],
        ActiveRecord::EVENT_AFTER_VALIDATE => ['attribute2', 'attribute1'],
    ]

public array $order = []
$preserveNonEmptyValues public property

Whether to preserve non-empty attribute values.

public boolean $preserveNonEmptyValues = false
$skipUpdateOnClean public property

Whether to skip this behavior when the `$owner` has not been modified

public boolean $skipUpdateOnClean = true

## Method Details

evaluateAttributes() public method

Evaluates the attributes values and assigns it to the current attributes.

public void evaluateAttributes ( $event )
$event | yii\base\Event |

events() public method

Declares event handlers for the $owner's events.

Child classes may override this method to declare what PHP callbacks should be attached to the events of the $owner component.

The callbacks will be attached to the $owner's events when the behavior is attached to the owner; and they will be detached from the events when the behavior is detached from the component.

The callbacks can be any of the following:

- method in this behavior: `'handleClick'`, equivalent to `[$this, 'handleClick']`
- object method: `[$object, 'handleClick']`
- static method: `['Page', 'handleClick']`
- anonymous function: `function ($event) { ... }`

The following is an example:

    [
        Model::EVENT_BEFORE_VALIDATE => 'myBeforeValidate',
        Model::EVENT_AFTER_VALIDATE => 'myAfterValidate',
    ]

public array events ( )
return | array | Events (array keys) and the corresponding event handler methods (array values).

getValue() protected method

Returns the value for the current attributes.

This method is called by evaluateAttributes(). Its return value will be assigned to the target attribute corresponding to the triggering event.

protected mixed getValue ( $attribute, $event )
$attribute | string | Target attribute name
$event | yii\base\Event | The event that triggers the current attribute updating.
return | mixed | The attribute value