Как обратиться к where

public function getUserGroups($user_id){

$this->select('g.id', 'id');
$this->select('g.*');

$this->joinInner('groups', 'g', 'g.id = i.group_id');

$this->filterEqual('user_id', $user_id);


if (!$this->order_by){
$this->orderBy('g.title');
}

return $this->get('groups_members');

}