Symfony 3.2检测到循环引用（配置限制：1）

Question

我的项目中有这两个实体

class PoliceGroupe
{
    /**
     * @var int
     *
     * @ORM\Column(name="id", type="integer")
     * @ORM\Id
     * @ORM\GeneratedValue(strategy="AUTO")
     */
    private $id;

    /**
     * @var string
     *
     * @ORM\Column(name="code", type="string", length=50)
     */
    private $code;

    /**
     * @ORM\ManyToMany(targetEntity="PointVente", inversedBy="policegroupe")
     * @ORM\JoinTable(name="police_groupe_point_vente",
     *      joinColumns={@ORM\JoinColumn(name="police_groupe_id", referencedColumnName="id")},
     *      inverseJoinColumns={@ORM\JoinColumn(name="point_vente_id", referencedColumnName="id")}
     *      )
     */
    private $pointVente;
    /**
     * Constructor
     */
    public function __construct($produit)
    {
       $this->pointVente = new \Doctrine\Common\Collections\ArrayCollection();
    }
}

这是我的另一个实体

class PointVente
{
    /**
     * @var string
     *
     * @ORM\Column(name="abb", type="string", length=50)
     */
    private $abb;

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

    /**
     *
     * @ORM\ManyToMany(targetEntity="PoliceGroupe", mappedBy="pointVente")
     */
    private $policegroupe;
    }

我试图在我的控制器中运行此代码

$encoders = array(new XmlEncoder(), new JsonEncoder());
$normalizers = array(new ObjectNormalizer());
$serializer = new Serializer($normalizers, $encoders);
$em = $this->getDoctrine()->getManager();
$data = $request->get('data');
$policegroupe=$em->getRepository('StatBundle:PoliceGroupe')->findOneBy(array('id' => $data));
$pointventes = $policegroupe->getPointVente();
$jsonContent = $serializer->serialize($pointventes, 'json');
return new JsonResponse( array('pointventes'=>$jsonContent) );

但我得到了这个例外

Symfony\Component\Serializer\Exception\CircularReferenceException: A circular reference has been detected (configured limit: 1).
    at n/a
        in C:\wamp\www\Sys\vendor\symfony\symfony\src\Symfony\Component\Serializer\Normalizer\AbstractNormalizer.php line 194

我根据学说注释映射了我的实体。我错过了什么吗？

Answer 1

Symfony 3.2

使用useCircularReferenceLimit方法。例如：

$normalizer = new ObjectNormalizer();
$normalizer->setCircularReferenceLimit(2);
// Add Circular reference handler
$normalizer->setCircularReferenceHandler(function ($object) {
    return $object->getId();
});
$normalizers = array($normalizer);
$serializer = new Serializer($normalizers, $encoders);

原因是当您尝试序列化它们时，实体中的循环引用会导致一些问题。该方法的作用是定义序列化层次结构的最大深度。

编辑：添加循环引用处理程序（A circular reference has been detected (configured limit: 1) Serializer SYMFONY）

EDIT : Update (Symfony 4.2)

要试用Symfony 3.2，但circular_reference_limit不是问题（默认为1是好的，否则你的实体将被检索2次），问题是circular_reference_handler处理实体的方式。告诉id是实体标识符可以解决问题。请参阅Symfony Docs at the bottom of this paragraph。

由于setCircularReferenceHandler被弃用in favour of the following keys of the context circular_reference_handler，我们可以写道：

// Tip : Inject SerializerInterface $serializer in the controller method
// and avoid these 3 lines of instanciation/configuration
$encoders = [new JsonEncoder()]; // If no need for XmlEncoder
$normalizers = [new ObjectNormalizer()];
$serializer = new Serializer($normalizers, $encoders);

// Serialize your object in Json
$jsonObject = $serializer->serialize($objectToSerialize, 'json', [
    'circular_reference_handler' => function ($object) {
        return $object->getId();
    }
]);

// For instance, return a Response with encoded Json
return new Response($jsonObject, 200, ['Content-Type' => 'application/json']);

Answer 2

修复了同样的问题

use JMS\Serializer\SerializerBuilder;
...

$products = $em->getRepository('AppBundle:Product')->findAll();
$serializer = SerializerBuilder::create()->build();
$jsonObject = $serializer->serialize($products, 'json');

阅读here