/**
  * Retrieve object using using composite pkey values.
  * @param      int $item_id
  * @param      int $class_id
  * @param      PropelPDO $con
  * @return     ReservationItemRights
  */
 public static function retrieveByPK($item_id, $class_id, PropelPDO $con = null)
 {
     $_instancePoolKey = serialize(array((string) $item_id, (string) $class_id));
     if (null !== ($obj = ReservationItemRightsPeer::getInstanceFromPool($_instancePoolKey))) {
         return $obj;
     }
     if ($con === null) {
         $con = Propel::getConnection(ReservationItemRightsPeer::DATABASE_NAME, Propel::CONNECTION_READ);
     }
     $criteria = new Criteria(ReservationItemRightsPeer::DATABASE_NAME);
     $criteria->add(ReservationItemRightsPeer::ITEM_ID, $item_id);
     $criteria->add(ReservationItemRightsPeer::CLASS_ID, $class_id);
     $v = ReservationItemRightsPeer::doSelect($criteria, $con);
     return !empty($v) ? $v[0] : null;
 }