Doctrine inverse side's collection field is randomly filled

I have the following two entities address and user . and in one of my controllers I have this function :

public function initAddressAction($idUser)
{
    $em = $this->getDoctrine()->getManager();
    $address = new Address();

    /** @var User $user*/
    $user= $em->getRepository('AppBundle:User' )->find($idUser);
    if ($user!== null) {
        $address->setUser($user); 
            dump($user); // #1
            $addresses = $user->getAddresses()->toArray();
            dump($user);die; // #2
            ...}

My question is why the first dump prints the user object with an empty array in the addresses field :

#collection: Doctrine\Common\Collections\ArrayCollection {#9487 ▼

  -elements: []`

WHEREAS the second dump prints the user object with a non empty array collection in the addresses field (there is actually one address in this array):

#collection: Doctrine\Common\Collections\ArrayCollection {#9487 ▼

  -elements: array:1 [▼

    0 => App\Entity\address{#81625 ▼`

User :

/**
 * @ORM\OneToMany(targetEntity="App\Entity\Address", mappedBy="user")
 */
private $addresses;

/**
 * Set addresses
 *
 * @param Collection $addresses
 */
public function setAddresses($addresses)
{
    $this->addresses= $addresses;
}

/**
 * Get addresses
 *
 * @return \Doctrine\Common\Collections\Collection
 */
public function getAddresses()
{
    return $this->addresses;
}

/**
 * Add address
 *
 * @param Address $address
 * @return User
 */
public function addAddress(Address$address)
{
    if (!$this->addresses->contains($address)) {
        $this->addresses[] = $address;
    }

    return $this;
}

/**
 * Remove address
 *
 * @param Address $address
 */
public function removeAddress(Address $address)
{
    $this->addresses->removeElement($address);
}

Address :

/**
 * @ORM\ManyToOne(targetEntity="App\Entity\User", inversedBy="adresses")
 * @ORM\JoinColumn(name="id_user", referencedColumnName="id_user", nullable=false)
 */
private $user

/**
 * @return User
 */
public function getUser()
{
    return $this->user;
}

/**
 * @param User $user
 */
public function setUser($user)
{
    $this->user= $user;
}

Solution

I've generated a User and an Address class via the Symfony maker bundle.

User:

<?php

namespace App\Entity;

use App\Repository\UserRepository;
use Doctrine\Common\Collections\ArrayCollection;
use Doctrine\Common\Collections\Collection;
use Doctrine\ORM\Mapping as ORM;

/**
 * @ORM\Entity(repositoryClass=UserRepository::class)
 * @ORM\Table(name="`user`")
 */
class User
{
    /**
     * @ORM\Id
     * @ORM\GeneratedValue
     * @ORM\Column(type="integer")
     */
    private $id;

    /**
     * @ORM\Column(type="string", length=255)
     */
    private $name;

    /**
     * @ORM\OneToMany(targetEntity=Address::class, mappedBy="userField")
     */
    private $addresses;

    public function __construct()
    {
        $this->addresses = new ArrayCollection();
    }

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

    public function getName(): ?string
    {
        return $this->name;
    }

    public function setName(string $name): self
    {
        $this->name = $name;

        return $this;
    }

    /**
     * @return Collection<int, Address>
     */
    public function getAddresses(): Collection
    {
        return $this->addresses;
    }

    public function addAddress(Address $address): self
    {
        if (!$this->addresses->contains($address)) {
            $this->addresses[] = $address;
            $address->setUserField($this);
        }

        return $this;
    }

    public function removeAddress(Address $address): self
    {
        if ($this->addresses->removeElement($address)) {
            // set the owning side to null (unless already changed)
            if ($address->getUserField() === $this) {
                $address->setUserField(null);
            }
        }

        return $this;
    }
}

Address:

<?php

namespace App\Entity;

use App\Repository\AddressRepository;
use Doctrine\ORM\Mapping as ORM;

/**
 * @ORM\Entity(repositoryClass=AddressRepository::class)
 */
class Address
{
    /**
     * @ORM\Id
     * @ORM\GeneratedValue
     * @ORM\Column(type="integer")
     */
    private $id;

    /**
     * @ORM\ManyToOne(targetEntity=User::class, inversedBy="addresses")
     * @ORM\JoinColumn(nullable=false)
     */
    private $userField;

    /**
     * @ORM\Column(type="string", length=255)
     */
    private $name;

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

    public function getUserField(): ?User
    {
        return $this->userField;
    }

    public function setUserField(?User $userField): self
    {
        $this->userField = $userField;

        return $this;
    }

    public function getName(): ?string
    {
        return $this->name;
    }

    public function setName(string $name): self
    {
        $this->name = $name;

        return $this;
    }
}

Example that fails:

Try this (in a controller for example):

    // get address 1 (this is attached to user 1 in the database)
    $address1 = $addressRepo->findOneBy(['id' => 1]);
    dump($address1);

This is Address 1, its User object has not been initalized yet, but that's not important for this example.

    // get user 2 (user 2 only has address 2 in the database)
    $user2 = $userRepo->findOneBy(['id' => 2]);
    dump($user2);

This is User 2, notice that the Address array is not initialized yet (this is important!).

    // set user 2 onto address 1
    $address1->setUserField($user2);
    dump($address1);

Now Address 1 has User 2.

    dump($user2);

But User 2 does not have Address 1.

    // load user 2's addresses from the database
    $user2->getAddresses()->toArray();
    dump($user2);

User 2 now has it's Address 2 loaded from the database (still no Address 1 though).

With $userField->addAddress($this)

If you add the $userField->addAddress($this); line:

public function setUserField(?User $userField): self
{
    $this->userField = $userField;
    $userField->addAddress($this);

    return $this;
}

And execute the same steps:

    // get address 1 (this is attached to user 1 in the database)
    $address1 = $addressRepo->findOneBy(['id' => 1]);
    dump($address1);

    // get user 2  (user 2 only has address 2 in the database)
    $user2 = $userRepo->findOneBy(['id' => 2]);
    dump($user2);

    // set user 2 onto address 1
    $address1->setUserField($user2);
    dump($address1);
    dump($user2);

User 2 now does have Address 1. Adding the Address to the User also triggers the loading of the existing Adresses from the database, so it now also has Address 2.

    // load user 2's addresses from the database
    $user2->getAddresses()->toArray();
    dump($user2);

(The Addresses were already loaded, no changes.)

With persist & flush

And if you do not add the $userField->addAddress($this); line, but add persist & flush:

    // get address 1 (this is attached to user 1 in the database)
    $address1 = $addressRepo->findOneBy(['id' => 1]);
    dump($address1);

    // get user 2  (user 2 only has address 2 in the database)
    $user2 = $userRepo->findOneBy(['id' => 2]);
    dump($user2);

    // set user 2 onto address 1
    $address1->setUserField($user2);
    dump($address1);
    dump($user2);

User 2 does not have Address 1.

    // persist address 1
    $em->persist($address1);
    $em->flush($address1);

    // load user 2's addresses from the database
    $user2->getAddresses()->toArray();
    dump($user2);

Now User 2 has both Address 1 and Address 2 loaded from the database.