Doctrine\ODM\MongoDB\DocumentRepository::findOneBy PHP Method

    public function findOneBy(array $criteria)
    {
        return $this->getDocumentPersister()->load($criteria);
    }

 /**
  * Performs an authentication
  * @param  array
  * @return Nette\Security\Identity
  * @throws Nette\Security\AuthenticationException
  */
 public function authenticate(array $credentials)
 {
     list($email, $password) = $credentials;
     $user = $this->adminRepository->findOneBy(['email' => $email]);
     if (!$user or !$this->passwordHasher->checkPassword($password, $user->getPassword())) {
         throw new NS\AuthenticationException("Invalid credentials", self::FAILURE);
     }
     return $user;
 }