private function replaceConstants(Gpf_Data_Record $row) {
     $coupon = new Pap_Db_Coupon();
     $coupon->setId($row->get('id'));
     $coupon->setCode($row->get('code'));
     $coupon->setStatus($row->get('status'));
     $coupon->set(Pap_Db_Table_Coupons::MAX_USE_COUNT, $row->get('limit_use'));
     $coupon->set(Pap_Db_Table_Coupons::VALID_FROM, $row->get('valid_from'));
     $coupon->set(Pap_Db_Table_Coupons::VALID_TO, $row->get('valid_to'));
     $row->add('coupon', $this->banner->getCouponText($coupon));                
     $row->add('validity', $coupon->isValid());
 }