public function count(Criteria $criteria)
{
$identifiers = $this->metadata->getIdentifier();
$identifierName = reset($identifiers);
$qb = $this->repository->createQueryBuilder('e');
$this->buildWhereClause($qb, $criteria);
return $qb->select("count(e.{$identifierName})")->getQuery()->getSingleScalarResult();
}