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Undoubtedly will need to update “Creating Your Own Behavior” to reflect changes in Yii 2.
90 lines
2.8 KiB
Markdown
90 lines
2.8 KiB
Markdown
Behaviors
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=========
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A behavior (also knows as *mixin*) can be used to enhance the functionality of an existing component without modifying the component's
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code. In particular, a behavior can "inject" its own methods and properties into the component, making them directly accessible
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via the component itslef. A behavior can also respond to events triggered in the component, thus intercepting the normal
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code execution. Unlike [PHP's traits](http://www.php.net/traits), behaviors can be attached to classes at runtime.
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Using behaviors
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---------------
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A behavior can be attached to any class that extends from `Component`. In order to attach a behavior to a class, the component class must implement the `behaviors`
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method. As an example, Yii provides the `AutoTimestamp` behavior for automatically updating timestamp fields when saving an Active Record model:
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```php
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class User extends ActiveRecord
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{
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// ...
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public function behaviors()
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{
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return [
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'timestamp' => [
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'class' => 'yii\behaviors\AutoTimestamp',
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'attributes' => [
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ActiveRecord::EVENT_BEFORE_INSERT => ['create_time', 'update_time'],
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ActiveRecord::EVENT_BEFORE_UPDATE => 'update_time',
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],
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],
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];
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}
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}
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```
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In the above, the `class` value is a string representing the fully qualified behavior class name. All of the other key-value pairs represent corresponding public properties of the `AutoTimestamp` class, thereby customizing how the behavior functions.
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Creating your own behaviors
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---------------------------
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[[NEEDS UPDATING FOR Yii 2]]
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To create your own behavior, you must define a class that implements the `IBehavior` interface. This can be accomplished by extending `CBehavior`. More specifically, you can extend `CModelBehavior` or `CActiveRecordBehavior` for behaviors to be used specifically with models or with Active Record models.
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```php
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class MyBehavior extends CActiveRecordBehavior
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{
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}
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```
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To make your behavior customizable, like `AutoTimestamp`, add public properties:
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```php
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class MyBehavior extends CActiveRecordBehavior
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{
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public $attr;
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}
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```
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Now, when the behavior is used, you can set the attribute to which you'd want the behavior to be applied:
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```php
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class User extends ActiveRecord
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{
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// ...
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public function behaviors()
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{
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return [
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'mybehavior' => [
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'class' => 'ext\mybehavior\MyBehavior',
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'attr' => 'member_type'
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],
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],
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];
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}
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}
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```
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Behaviors are normally written to take action when certain model-related events occur, such as `beforeSave` or `afterFind`. You can write your behaviors to have the corresponding method. Within the method, you can access the model instance through `$this->getOwner()`:
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```php
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class MyBehavior extends CActiveRecordBehavior
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{
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public $attr;
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public function beforeSave() {
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$model = $this->getOwner();
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// Use $model->$attr
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}
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}
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``` |