recursive get parents

MyModel.php

class MyModel extends CActiveRecord 
{

    public function relations() 
    {
        return array(
            'parent' => array(
                self::BELONGS_TO,
                'MyModel',
                'parent_id',
            ),
        );
    }
    public function getParents($parents = array())
    {
        if ($this->parent && !in_array($this->parent_id, array_keys($parents))) {
            $parents = $this->parent->getParents($parents);
        }
        $parents[$this->id] = $this;
        return $parents
    }

}