Doctrine entity manager find by empty array collection - php

Question

I have an entity called Cycle, with a OneToMany association to CycleActeur (see code below).
I'd like to be able to fetch all Cycle objets in database with no CycleActeur objects associated, using a simple doctrine findBy* method from my controller.
That is to say something like this :
$manager = $this->getContainer()->get('doctrine.orm.entity_manager');
$cycleManager = $manager->getRepository('ESI67Zen2Bundle:Cycle');
$cyclesWithNoCycleActeur = $cycleManager->findBy('acteurs', null);
Is there a way to do this without having to write a specific method in the CycleRepository ?
Extract from the Cycle class code
class Cycle {
/**
* #ORM\OneToMany(
* targetEntity="CycleActeur",
* mappedBy="cycle",
* orphanRemoval=true)
*/
private $acteurs;
}
Extract from the Cycle class code
class CycleActeur {
/**
* #var Cycle Le cycle concerné
*
* #ORM\ManyToOne(targetEntity="Cycle", inversedBy="acteurs")
* #ORM\JoinColumn(name="cycle_id", referencedColumnName="id")
*
*/
private $cycle;
}

Answer 1

Your Cycle entity is the inverse side of relationship and it's table in database has no 'acteurs' column, so you cannot use findBy(['acteurs'=>null]) or findByActeurs(null). But you can do something anyway:
$manager = $this->getContainer()->get('doctrine.orm.entity_manager');
$cycleManager = $manager->getRepository('ESI67Zen2Bundle:Cycle');
$allCycles = $cycleManager->findAll();
$cyclesWithNoCycleActeur = [];
foreach($allCycles as $cycle)
{
if($cycle->getActeurs()->isEmpty())
{
$cyclesWithNoCycleActeur[] = $cycle;
}
}

Answer 2

In this case (to my mind) the best way is to use DQL's condition IS EMPTY:
$manager
->createQueryBuilder()
->from(Cycle::class, 'cycle')
->select('cycle')
->andWhere('cycle.acteurs IS EMPTY')
->getQuery()
->getResult()
;
You can use this code in the EntityRepository or anywhere you have access to the EntityManager.
Source: Doctrine documentation.

Answer 3

There's a DQL function SIZE(), which according to Doctrine documentation:
SIZE(collection) - Return the number of elements in the specified collection
So you can use it as a condition like:
SIZE(acteurs) = 0
I'm not sure if it will work with a findBy method, but I would recommend to create a custom method in ESI67Zen2Bundle:Cycle's repository, to make it explicit what the code is doing. Its will work both for DQL Query and Query Builder.

Answer 4

$cyclesWithNoCycleActeur = $cycleManager->findBy(array('SIZE(acteurs)' => 0));
My 2 cents