Add distinct values to array collection

Within my application I am sending out notifications to different users, which are assigned to agencies, which are assigned to documents. So whenever a document gets created and an agency is assigned to that document, all the users belonging to that agency should get a notification. The problem: it may happen, that an user is assigned to multiple agencies so whenever the notifications get sent out and all his agencies are assigned to the document, he would get notified multiple times. I'd like to avoid this but I can't figure out how to add only distinct objects to my array collection since it doesn't seem like there's something like the array_unique function.

So far it looks like that:

 foreach($document->getAgencies() as $agency) {
     if(count($agency->getUseragencies()) > 0){
      $users = $agency->getUseragencies();
      foreach ($users as $user){
      ... notifications are generated
      $manager->addNotification($user, $notif);
     }
  }
}

Any help would be appreciated! oh and background info: Agency is an own entity, as well as User is and they are in a many to many relationship!

edit mapping infos: in entity Agency:

/**
* @ORM\ManyToMany(targetEntity="UserBundle\Entity\User", mappedBy="agencies")
**/
private $useragencies;

in entity User

        /**
     * @ORM\ManyToMany(targetEntity="AppBundle\Entity\Agency", inversedBy="useragencies", cascade={"persist"})
     * @ORM\JoinTable(name="user_user_agencies",
     *   joinColumns={@ORM\JoinColumn(name="user_id", referencedColumnName="id")},
     *   inverseJoinColumns={@ORM\JoinColumn(name="iata8", referencedColumnName="iata8")})
     * @var \AppBundle\Entity\Agency
     **/
    private $agencies;



        /**
     * @ORM\OneToMany(targetEntity="AppBundle\Entity\Notification", mappedBy="user", orphanRemoval=true, cascade={"persist"})
     **/

    private $notifications;

Solution

I assume your Agency entity has also bidirectional mapping with Document entity i guess as ManyToMany. To get the users whom you want to send the notification which belongs to multiple agencies and an agency can have many documents you can use below DQL to get distinct users by providing the document id if you have any other property to identify the document you can adjust WHERE clause accordingly

SELECT DISTINCT u
FROM YourBundle:User u
JOIN u.agencies a
JOIN a.documents d
WHERE d.id = :documentid

Using query builder it would be something like

$user = $em->getRepository('YourBundle:User'); 
$user = $user->createQueryBuilder('u')
        ->select('u')
        ->join('u.agencies','a')
        ->join('a.documents','d')
        ->where('d.id = :documentid')
        ->setParameter('documentid', $documentid)
        ->distinct()
        ->getQuery();
$users= $user->getResult();