public function existVoteUser(Photo $photo, $user)
 {
     //todo : vérifier l'user
     $qb = $this->createQueryBuilder('v');
     $qb->where('v.photo = :photo')->setParameter('photo', $photo->getId())->andWhere('v.user = :user')->setParameter('user', $user);
     return $qb->getQuery()->getResult();
 }
 public function getCommentairesByPhotoDesc(Photo $photo)
 {
     $qb = $this->createQueryBuilder('c');
     $qb->join('c.photo', 'p')->where('p.id = :id')->setParameter('id', $photo->getId())->orderBy('c.createdAt', 'DESC');
     return $qb->getQuery()->getResult();
 }