Symfony + JMSSerializer throw 500 - handleCircularReference

I'm trying to use the JMSSerializer with Symfony to build a simple json api.

So i have 2 simple Entities (1 User can have many Cars, each Car belongs to one User):

class Car
{
    /**
     * @ORM\Id()
     * @ORM\GeneratedValue()
     * @ORM\Column(type="integer")
     */
    private $id;

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

    /**
     * @ORM\ManyToOne(targetEntity="App\Entity\User", inversedBy="cars")
     * @ORM\JoinColumn(nullable=false)
     */
    private $user;
}

class User extends BaseUser
{
    /**
     * @ORM\Id
     * @ORM\Column(type="integer")
     * @ORM\GeneratedValue(strategy="AUTO")
     */
    protected $id;

    /**
     * @ORM\OneToMany(targetEntity="App\Entity\Car", mappedBy="user", orphanRemoval=true)
     */
    private $cars;
}

Now i want to get all Cars with their User.

My Controller:

class CarController extends AbstractController
{
    /**
     * @param CarRepository $carRepository
     *
     * @Route("/", name="car_index", methods="GET")
     *
     * @return Response
     */
    public function index(CarRepository $carRepository)
    {
        $cars = $carRepository->findAll();
        $serializedEntity = $this->container->get('serializer')->serialize($cars, 'json');

        return new Response($serializedEntity);
    }
}

This will throw a 500 error:

A circular reference has been detected when serializing the object of class \"App\Entity\Car\" (configured limit: 1)

Ok, sounds clear. JMS is trying to get each car with the user, and go to the cars and user ....

So my question is: How to prevent this behaviour? I just want all cars with their user, and after this, the iteration should be stopped.

You need to add max depth checks to prevent circular references. This can be found in the documentation here

Basically you add the @MaxDepth(1) annotation or configure max_depth if you're using XML/YML configuration. Then serialize like this:

use JMS\Serializer\SerializationContext;

$serializer->serialize(
    $data,
    'json',
    SerializationContext::create()->enableMaxDepthChecks()
);

Example Car class with MaxDepth annotation:

class Car
{
    /** 
     * @\JMS\Serializer\Annotation\MaxDepth(1)
     *
     * [..]
     */
     private $user;