public function getDomains()
    {
        $q = $this
            ->createQueryBuilder('m')
            ->select('m.domain')
            ->distinct()
            ->orderBy('m.domain');

        $ret = array();
        foreach ($q->getQuery()->execute() as $result) {
            $ret[$result['domain']] = $result['domain'];
        }
        return $ret;
    }