public function has($id)
    {
        try {
             $em = $this->entityManager->getDoctrineEntityManager();
             $data = $em->getRepository($this->getEntityClass())->findOneBy(array(
                 'id' => $id,
             ));
             
             if ($data !== null) {
                 return true;
             }
             
             return false;
        } catch (\Exception $e) {
            throw new Exception('Cannot check if there is an entity for the given id "' . $id . '".', 0, $e);
        }
    }