protected function doClean($value)
 {
     $criteria = new Criteria();
     $criteria->add(EmailPeer::EMAIL, $value);
     $criteria->add(EmailPeer::IS_PRIMARY, true);
     $object = EmailPeer::doSelectOne($criteria);
     if (is_null($object)) {
         throw new sfValidatorError($this, 'invalid', array('value' => $value));
     }
     return $object->getUserId();
 }