Symfony2 AJAX Login

I have an example where I am trying to create an AJAX login using Symfony2 and FOSUserBundle. I am setting my own success_handler and failure_handler under form_login in my security.yml file.

Here is the class:

class AjaxAuthenticationListener implements AuthenticationSuccessHandlerInterface, AuthenticationFailureHandlerInterface
{  
    /**
     * This is called when an interactive authentication attempt succeeds. This
     * is called by authentication listeners inheriting from
     * AbstractAuthenticationListener.
     *
     * @see \Symfony\Component\Security\Http\Firewall\AbstractAuthenticationListener
     * @param Request        $request
     * @param TokenInterface $token
     * @return Response the response to return
     */
    public function onAuthenticationSuccess(Request $request, TokenInterface $token)
    {
        if ($request->isXmlHttpRequest()) {
            $result = array('success' => true);
            $response = new Response(json_encode($result));
            $response->headers->set('Content-Type', 'application/json');
            return $response;
        }
    }

    /**
     * This is called when an interactive authentication attempt fails. This is
     * called by authentication listeners inheriting from
     * AbstractAuthenticationListener.
     *
     * @param Request                 $request
     * @param AuthenticationException $exception    
     * @return Response the response to return
     */
    public function onAuthenticationFailure(Request $request, AuthenticationException $exception)
    {
        if ($request->isXmlHttpRequest()) {
            $result = array('success' => false, 'message' => $exception->getMessage());
            $response = new Response(json_encode($result));
            $response->headers->set('Content-Type', 'application/json');
            return $response;
        }
    }
}

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