public function getActiveSiteTheme($siteId)
    {
        $qb = $this->getEntityManager()->createQueryBuilder();
        /** @var $query \Doctrine\ORM\Query */

        $query = $qb->select('e, t')
            ->from($this->_entity, 'e')
            ->innerJoin('e.themeId', 't')
            ->where('e.siteId = :id')
            ->andWhere('e.isActive = 1')
            ->setMaxResults(1)
            ->setParameter('id', $siteId)
            ->getQuery();

        /** @var $result \PageBuilder\Entity\Join\SiteTheme */
        $result = $query->getOneOrNullResult(AbstractQuery::HYDRATE_OBJECT);
        if ($result) {
            return $result->getThemeId();
        } else {
            return $result;
        }
    }