FOSCommentBundle and thread_id

Question

I've followed FOSComment's instruction to have multiple threads in one page. It's ok everything works. Just kidding, the world isn't that beautiful.

I'll try to explain my problem : When I submit my comment, i've got Integrity constraint violation due to the URL, I don't pass any Thread_id in my URL.

I found the piece of code in my controller which does that, but I've got no idea how to correct it. So, there's my controller :

public function indexAction(Request $request)
{
    $stmt = $this->getDoctrine()->getEntityManager()
        ->getConnection()
        ->prepare('select ttrss_entries.id, title, content, body, thread_id '
                . 'FROM ttrss_entries '
                . 'LEFT JOIN ttrss_tags ON ttrss_entries.id = ttrss_tags.post_int_id '
                . 'LEFT JOIN comment on comment.thread_id = ttrss_entries.id '
                . 'WHERE ttrss_tags.tag_name = "politique" '
                . 'GROUP BY ttrss_entries.id');
    $stmt->execute();
    $result = $stmt->fetchAll();

    //Here my problem
    $id = 'thread_id';
    $thread = $this->container->get('fos_comment.manager.thread')->findThreadById($id);
    if (null === $thread) {
    $thread = $this->container->get('fos_comment.manager.thread')->createThread();
    $thread->setId($id);
    $thread->setPermalink($request->getUri());

    $this->container->get('fos_comment.manager.thread')->saveThread($thread);
    }

    $comments = $this->container->get('fos_comment.manager.comment')->findCommentTreeByThread($thread);

    return $this->render('AppBundle:Politique:index.html.twig', array(
        'comments' => $comments,
        'thread' => $thread,
        'entities' => $result,
         ));


}

Here my view :

<div class="fos_comment_thread" data-thread-id="{{ thread.id }}">
 {% include 'FOSCommentBundle:Thread:comments.html.twig' with {
        'comments': comments,
        'thread': thread
 } %}

Thanks in advance for your help

PS : I'm a newbie with Symfony.