Documentation's behavior needs clarification

[tebazil]

In the documentation: https://github.com/yiisoft/yii2/blob/master/docs/guide/concept-behaviors.md#handling-component-events
This example

namespace app\components;

use yii\db\ActiveRecord;
use yii\base\Behavior;

class MyBehavior extends Behavior
{
    // ...

    public function events()
    {
        return [
            ActiveRecord::EVENT_BEFORE_VALIDATE => 'beforeValidate',
        ];
    }

    public function beforeValidate($event)
    {
        // ...
    }
}

is questionable, since, if I get behavior logic right, beforeValidate($event) should be triggered, as it is default handler for the ActiveRecord::EVENT_BEFORE_VALIDATE.

If I am right, we should expand on "default" handlers in text and add some custom name for a handler method, as it is rather confusing.

If I am understanding the mechanism wrong, than the issue is invalid and issue should be closed. In this case, I ask somebody of the contributors to answer my design questions in the forum:

• http:https://www.yiiframework.com/forum/index.php/topic/57081-why-does-beforeaction-in-actionfilter-runs-without-events-defined/
• http:https://www.yiiframework.com/forum/index.php/topic/57064-understanding-yii2-behaviors-events-management/

Thanks.

[qiangxue]

There's no such thing as default event handler. Where did you get this understanding from?

[tebazil]

@qiangxue ,
In Yii 1.1, there was CActiveRecordBehavior, which defined typical AR events and their handlers itself. Most of the time we had no need to override it.

class CActiveRecordBehavior extends CModelBehavior
{
...
public function events()
{
return array_merge(parent::events(), array(
'onBeforeSave'=>'beforeSave',
'onAfterSave'=>'afterSave',
'onBeforeDelete'=>'beforeDelete',
'onAfterDelete'=>'afterDelete',
'onBeforeFind'=>'beforeFind',
'onAfterFind'=>'afterFind',
'onBeforeCount'=>'beforeCount',
));
}
....

So I thought it's a typical approach throughout the system - to provide default method handler names.
I was wrong.
The issue is invalid for those who know the architecture of the framework.

However, from the user's point of view, who is migrating from v1 to v2, the issue remains.

We are used to extend from CActiveRecordBehavior and to provide no events() ourselves. Now there is no such a behavior, we are extending from Behavior and need to provide events().
This might be confusing for the users, don't you think?

[qiangxue]

The events() syntax is still the same. Neither 1.1 nor 2.0 has the such default event handler thing.

The only thing changed is that we dropped ActiveRecordBehavior in 2.0. So if you want to write a AR behavior and respond to some of its events, you have to do this yourself now by writing events().

[tebazil]

So if you want to write a AR behavior and respond to some of its events, you have to do this yourself now by writing events().

I think this should be in the documentation to prevent confusion. Mainly that was what the issue is about.

[tebazil]

Another argument to support this is that most of the behaviors written seem to be extending CActiveRecordBehavior.

[qiangxue]

Added the doc as suggested. Thanks.