Doctrine\ORM\EntityManager::merge PHP Méthode

    public function merge($entity)
    {
        if ( ! is_object($entity)) {
            throw new \InvalidArgumentException(gettype($entity));
        }
        $this->errorIfClosed();
        return $this->unitOfWork->merge($entity);
    }

 /**
  * The actual listener, will store the objects in the database
  *
  * @param IndexUpdateEvent $event
  */
 public function onIndexUpdate(IndexUpdateEvent $event)
 {
     $objects = $event->getObjects();
     foreach ($objects as $indexItem) {
         $this->em->merge($indexItem);
     }
     $this->em->flush();
 }