public function getModels()
    {
        try {
            $q = $this->createQueryBuilder('l')
                    ->where('l._site IS NULL')
                    ->orderBy('l._label', 'ASC')
                    ->getQuery();

            return $q->getResult();
        } catch (\Doctrine\ORM\NoResultException $e) {
            return;
        } catch (Exception $e) {
            return;
        }
    }