yiisoft/yii2 — pull request #1033 by resurtm (2013-10-21 13:29:41+00:00)
Title: Enhance kind of values accepted in $className of ExistValidator and UniqueValidator

Usage sample:

```php
namespace frontend\models;

class User extends \common\models\User
{
public function rules()
{
return [
['group_id', 'unique', 'className' => 'Group',
'attributeName' => 'id'],

['region_id', 'unique', 'className' => '\common\models\Region',
'attributeName' => 'id'],

['username', 'unique'],
];
}
}

class Group extends \common\models\Group
{
}

namespace common\models;

class Region extends \yii\db\ActiveRecord
{
}
```