public function preFlush(Room $room, PreFlushEventArgs $args)
  {
    $em = $args->getEntityManager();
    $parent = $room->getStore()->getParent();
    $rsm = new ResultSetMapping();
    $rsm->addScalarResult('COUNT(product_id)', 'count');

    $query = $em->createNativeQuery(
      'select COUNT(product_id)
            from room_product where `room_id` in
            (select id from room where store_id in
            (select id from store where parent_id = :parentId))', $rsm);
    $query->setParameter('parentId', $parent->getId());
    $result = $query->getOneOrNullResult();
    $parent->setNumberOfServices($result['count']);
    $em->persist($parent);
    $em->flush();
  }

public function preFlush(Room $room, PreFlushEventArgs $args)
  {
    $em = $args->getEntityManager();
    $numOfProducts = 0;
    $parent = $room->getStore()->getParent();
    foreach($parent->getStores() as $store) {
      foreach($store->getRooms() as $room) {
        $numOfServices += count($room->getProducts());
      }
    }
    $parent->setNumberOfProducts($numOfProducts);
    $classMetadata = $em->getClassMetadata(get_class($parent));
    $em->getUnitOfWork()->computeChangeSet($classMetadata, $parent);
  }