Ojs\OAIBundle\Controller\DefaultController::listIdentifierAction PHP Method

    public function listIdentifierAction(Request $request)
    {
        $data = [];
        /** @var \Doctrine\ORM\EntityManager $em */
        $em = $this->getDoctrine()->getManager();
        $qb = $em->createQueryBuilder();
        $qb->select("a")->from("OjsJournalBundle:Article", 'a');
        $qb->andWhere('a.status = ' . ArticleStatuses::STATUS_PUBLISHED);
        $set = $request->get("set", false);
        if ($set) {
            $qb->join("a.journal", "j", "WITH");
            $qb->where($qb->expr()->gte('j.slug', ':slug'))->setParameter('slug', $set);
        }
        $data['articles'] = $qb->getQuery()->getResult();
        return $this->response("OjsOAIBundle:Default:identifiers.xml.twig", $data);
    }