the simplest form of Symfony controller

MyController.php

<?php

namespace AppBundle\Controller;

use Exception;
use Sensio\Bundle\FrameworkExtraBundle\Configuration\Method;
use Sensio\Bundle\FrameworkExtraBundle\Configuration\Route;
use Symfony\Bundle\FrameworkBundle\Controller\Controller;
use Symfony\Component\HttpFoundation\JsonResponse;

class MyController extends Controller
{
    /**
     * @Route("/foobar", name="foobar")
     * @Method("GET")
     *
     * @return JsonResponse
     * @throws Exception
     */
    public function indexAction(): JsonResponse
    {
        $em = $this->getDoctrine()->getManager();

        var_dump($em);

        return new JsonResponse("{}");
    }
}