Ojs\JournalBundle\Entity\Subject::getId PHP Method

    public function getId()
    {
        return $this->id;
    }

 /**
  * @param string $institution
  */
 public function getByInstitutionAndSubject($institution, Subject $subject)
 {
     $qb = $this->createQueryBuilder('j');
     $qb->join('j.institution', 'i', 'WITH', 'i.slug=:institution')->join('j.subjects', 's', 'WITH', 's.id=:subject')->setParameter('institution', $institution)->setParameter('subject', $subject->getId());
     return $qb->getQuery()->getResult();
 }