public function listIdentifierAction(Request $request)
{
/** @var EntityManager $em */
$em = $this->getDoctrine()->getManager();
$slug = $request->get('slug', false);
$this->throw404IfNotFound($slug);
$builder = $em->createQueryBuilder();
$builder->select('article')->from('OjsJournalBundle:Article', 'article');
$builder->join('article.journal', 'journal', 'WITH');
$builder->where($builder->expr()->eq('journal.slug', ':slug'))->setParameter('slug', $slug);
$data = ['records' => $builder->getQuery()->getResult()];
return $this->response('OjsOAIBundle:Journal:identifiers.xml.twig', $data);
}