Symfony2表单为什么我的表单返回警告：json_encode（）：检测到递归？

I have to entities, Applications and Votes.

The idea is to relate many to one. So Applications have many Votes and one Vote is for one Application.

In my entities class I have settings like this:

Application Entity Class:

\/**
\* @ORM\OneToMany(targetEntity="Vote", mappedBy="application")
\*/
\private $votes;

Vote Entity Class:

\/**
\* @ORM\ManyToOne(targetEntity="Application", inversedBy="votes")
\* @ORM\JoinColumn(referencedColumnName="id")
\*/
\private $application;

I think this relation is set up well or am I mistaken ?

Next thing is that I have a form builder class for only one field:

$builder->add('rate')
    ->add('save', 'submit');

The Votes entity has fields: (id, username, rate, createdAt, updatedAt, application)

and in my controller I'm doing something like this:

    $vote = new Vote();
    $form = $this->createForm(new VoteType(), $vote);

    $form->handleRequest($this->getRequest());

    if ($form->isValid()) {
        $vote->setUserName($tenant->getUsername());
        $vote->setApplication($app);
        $em->persist($vote);
        $em->flush();

        $this->get('session')->getFlashBag()->add('success', 'Oceniono aplikację.');

        return $this->redirect($this->generateUrl('applications_main'));
    }

    return array( 'form' => $form->createView(), );

and it isn't working, it returns me error:

ContextErrorException: Warning: json_encode(): recursion detected in E:\wamp\www\project\vendor\symfony\symfony\src\Symfony\Component\HttpFoundation\JsonResponse.php line 92

stack trace (plain text): http://pastebin.com/bSQTDJQY

Entities are prone to recursive issues, if you var_dump or print_r an entitiy, it will hang.

One of the best serialization tools that is capable of turning an entity into a hierarchal non-recursive tree is: https://github.com/schmittjoh/JMSSerializerBundle

It is used with FOSRestBundle as part of its transparent acceptable response handing.

You are having a similar issue to this: Avoiding recursion with Doctrine entities and JMSserializer

Check out the solution, and try using JMSSerializer.

Edit: Other likely cause:

When you return the array you are returning the form contained within that array. Your event listener is trying to serialize this as json, this is both a cause of issues as well as being relatively pointless unless the form is being used to provide an augmented data template.

Either way, a form cannot be serialized so simply, did you even mean to do that?