How to use events in yii2?

Question

I\'ve been through the documentation and all the articles on Yii2 events found using Google. Can someone provide me a good example of how events can be used in

Answer 1

For "global" events.

Optionally you can create a specialized event class

namespace  your\handler\Event\Namespace;
class EventUser extends Event {
   const EVENT_NEW_USER = 'new-user';
}

define at least one handler class:

namespace  your\handler\Event\Namespace;
class handlerClass{
    // public AND static
    public static function handleNewUser(EventUser $event)
    {
        // $event->user contain the "input" object
        echo 'mail sent to admin for'. $event->user->username;
    }
}

Inside the component part of the config under (in this case) the user component insert you event:

'components' => [
  'user' => [
    ...
    'on new-user' => ['your\handler\Event\Namespace\handlerClass', 'handleNewUser'],
  ],
  ...
]

Then in your code you can trigger the event:

Yii::$app->user->trigger(EventUser::EVENT_NEW_USER, new EventUser($user));

ADD

You can also use a closure:

• allows IDE to "detect" the use of the function (for code navigation)
• put some (small) code that manage the event

example:

'components' => [
  'user' => [
    ...
    'on new-user' => function($param){ your\handler\Event\Namespace\handlerClass::handleNewUser($param);},
    'on increment' => function($param){ \Yii::$app->count += $param->value;},
  ],   
  ... 
]