symfony - How to return Repository Objects as Json on Symfony2

Question

I'm trying to return the users like this, but of course it doesn't work, I need the data as JSon since im working with BackboneJs

/**
* @Route("/mytest",name="ajax_user_path")
*/
public function ajaxAction()
{
    $em = $this->get('doctrine')->getManager();
    $users = $this->get('doctrine')->getRepository('GabrielUserBundle:Fosuser')->findAll();

    $response = array("users"=>$users);            
    return new Response(json_encode($response));
}

Answer 1

Thanks for your help guys, here is the Solution Get the JMSSerializerBundle,

This is the code on the controller

/**
     * @Route("/user")
     * @Template()
     */
    public function userAction()
    {
        $em = $this->get('doctrine')->getManager();
        $users = $this->get('doctrine')->getRepository('GabrielUserBundle:Fosuser')->findAll();

        $serializer = $this->get('jms_serializer');
        $response = $serializer->serialize($users,'json');

        return new Response($response);
    }