# AttributesBehavior

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

[API reference](/docs/api/index.md) › [yii](/docs/api/yii/index.md) › [behaviors](/docs/api/yii/behaviors/index.md) › AttributesBehavior

| class | `yii\behaviors\AttributesBehavior` |
| --- | --- |
| Extends | [`yii\base\Behavior`](/docs/api/yii/base/behavior/index.md) » [`yii\base\BaseObject`](/docs/api/yii/base/baseobject/index.md) |
| Implements | [`yii\base\Configurable`](/docs/api/yii/base/configurable/index.md) |
| Since | 2.0.13 |
| Source | [`framework/behaviors/AttributesBehavior.php`](https://github.com/yiisoft/yii2/blob/22.0/framework/behaviors/AttributesBehavior.php#L69) |

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

To use AttributesBehavior, configure the [`$attributes`](/docs/api/yii/behaviors/attributesbehavior/index.md#property-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::class,
            '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()](/docs/api/yii/base/model/index.md#method-rules) method of the model.

## Properties

| Property | Type | Description | Defined by |
| --- | --- | --- | --- |
| [`$attributes`](#property-attributes) | `array` | List of attributes that are to be automatically filled with the values specified via enclosed arrays. Default: `[]`. | `AttributesBehavior` |
| [`$order`](#property-order) | `array` | List of order of attributes that are to be automatically filled with the event. Default: `[]`. | `AttributesBehavior` |
| <span id="property-owner"></span>[`$owner`](/docs/api/yii/base/behavior/index.md#property-owner) | `yii\base\T\|null` | The owner of this behavior Default: `null`. | [`yii\base\Behavior`](/docs/api/yii/base/behavior/index.md) |
| <span id="property-preserveNonEmptyValues"></span>`$preserveNonEmptyValues` | `bool` | Whether to preserve non-empty attribute values. Default: `false`. | `AttributesBehavior` |
| <span id="property-skipUpdateOnClean"></span>`$skipUpdateOnClean` | `bool` | Whether to skip this behavior when the `$owner` has not been modified Default: `true`. | `AttributesBehavior` |

## Methods

| Method | Description | Defined by |
| --- | --- | --- |
| <span id="method-__construct"></span>[`__construct()`](/docs/api/yii/base/baseobject/index.md#method-__construct) | Constructor. | [`yii\base\BaseObject`](/docs/api/yii/base/baseobject/index.md) |
| <span id="method-__call"></span>[`__call()`](/docs/api/yii/base/baseobject/index.md#method-__call) | Calls the named method which is not a class method. | [`yii\base\BaseObject`](/docs/api/yii/base/baseobject/index.md) |
| <span id="method-__get"></span>[`__get()`](/docs/api/yii/base/baseobject/index.md#method-__get) | Returns the value of an object property. | [`yii\base\BaseObject`](/docs/api/yii/base/baseobject/index.md) |
| <span id="method-__isset"></span>[`__isset()`](/docs/api/yii/base/baseobject/index.md#method-__isset) | Checks if a property is set, i.e. defined and not null. | [`yii\base\BaseObject`](/docs/api/yii/base/baseobject/index.md) |
| <span id="method-__set"></span>[`__set()`](/docs/api/yii/base/baseobject/index.md#method-__set) | Sets value of an object property. | [`yii\base\BaseObject`](/docs/api/yii/base/baseobject/index.md) |
| <span id="method-__unset"></span>[`__unset()`](/docs/api/yii/base/baseobject/index.md#method-__unset) | Sets an object property to null. | [`yii\base\BaseObject`](/docs/api/yii/base/baseobject/index.md) |
| <span id="method-attach"></span>[`attach()`](/docs/api/yii/base/behavior/index.md#method-attach) | Attaches the behavior object to the component. | [`yii\base\Behavior`](/docs/api/yii/base/behavior/index.md) |
| <span id="method-canGetProperty"></span>[`canGetProperty()`](/docs/api/yii/base/baseobject/index.md#method-canGetProperty) | Returns a value indicating whether a property can be read. | [`yii\base\BaseObject`](/docs/api/yii/base/baseobject/index.md) |
| <span id="method-canSetProperty"></span>[`canSetProperty()`](/docs/api/yii/base/baseobject/index.md#method-canSetProperty) | Returns a value indicating whether a property can be set. | [`yii\base\BaseObject`](/docs/api/yii/base/baseobject/index.md) |
| <span id="method-className"></span>[`className()`](/docs/api/yii/base/baseobject/index.md#method-className) static | Returns the fully qualified name of this class. | [`yii\base\BaseObject`](/docs/api/yii/base/baseobject/index.md) |
| <span id="method-detach"></span>[`detach()`](/docs/api/yii/base/behavior/index.md#method-detach) | Detaches the behavior object from the component. | [`yii\base\Behavior`](/docs/api/yii/base/behavior/index.md) |
| [`evaluateAttributes()`](#method-evaluateAttributes) | Evaluates the attributes values and assigns it to the current attributes. | `AttributesBehavior` |
| [`events()`](#method-events) | Declares event handlers for the [`$owner`](/docs/api/yii/base/behavior/index.md#property-owner)'s events. | `AttributesBehavior` |
| <span id="method-hasMethod"></span>[`hasMethod()`](/docs/api/yii/base/baseobject/index.md#method-hasMethod) | Returns a value indicating whether a method is defined. | [`yii\base\BaseObject`](/docs/api/yii/base/baseobject/index.md) |
| <span id="method-hasProperty"></span>[`hasProperty()`](/docs/api/yii/base/baseobject/index.md#method-hasProperty) | Returns a value indicating whether a property is defined. | [`yii\base\BaseObject`](/docs/api/yii/base/baseobject/index.md) |
| <span id="method-init"></span>[`init()`](/docs/api/yii/base/baseobject/index.md#method-init) | Initializes the object. | [`yii\base\BaseObject`](/docs/api/yii/base/baseobject/index.md) |
| [`getValue()`](#method-getValue) protected | Returns the value for the current attributes. | `AttributesBehavior` |

## Property details

### $attributes <span id="property-attributes"></span>

```php
public array $attributes = []
```

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](/docs/api/yii/db/expression/index.md) 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;
      },
  ],
]
```

### $order <span id="property-order"></span>

```php
public array $order = []
```

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`](/docs/api/yii/behaviors/attributesbehavior/index.md#property-attributes) for this attribute do not specify this event, it is ignored

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

## Method details

### evaluateAttributes() <span id="method-evaluateAttributes"></span>

```php
public function evaluateAttributes(yii\base\Event $event): mixed
```

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

**Parameters**

| Parameter | Type | Description |
| --- | --- | --- |
| `$event` | [`yii\base\Event`](/docs/api/yii/base/event/index.md) |  |

**Returns**

`mixed`

### events() <span id="method-events"></span>

```php
public function events(): array
```

Declares event handlers for the [`$owner`](/docs/api/yii/base/behavior/index.md#property-owner)'s events.

Child classes may override this method to declare what PHP callbacks should
be attached to the events of the [`$owner`](/docs/api/yii/base/behavior/index.md#property-owner) component.

The callbacks will be attached to the [`$owner`](/docs/api/yii/base/behavior/index.md#property-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',
]
```

**Returns**

`array`: Events (array keys) and the corresponding event handler methods (array values).

### getValue() <span id="method-getValue"></span>

```php
protected function getValue(string $attribute, yii\base\Event $event): mixed
```

Returns the value for the current attributes.

This method is called by [`evaluateAttributes()`](/docs/api/yii/behaviors/attributesbehavior/index.md#method-evaluateAttributes). Its return value will be assigned
to the target attribute corresponding to the triggering event.

**Parameters**

| Parameter | Type | Description |
| --- | --- | --- |
| `$attribute` | `string` | Target attribute name |
| `$event` | [`yii\base\Event`](/docs/api/yii/base/event/index.md) | The event that triggers the current attribute updating. |

**Returns**

`mixed`: The attribute value