php__symfony__book/src/Controller/SessionAwareController.php

<?php

namespace App\Controller;

use Sensio\Bundle\FrameworkExtraBundle\Configuration\Route;
use Symfony\Component\HttpFoundation\Request;
use Symfony\Component\HttpFoundation\Response;
use Symfony\Component\HttpFoundation\Session\SessionInterface;

/**
 * Class SessionAwareController demonstrates session usage.
 *
 * @package App\Controller
 */
class SessionAwareController {

  /**
   * @param \Symfony\Component\HttpFoundation\Session\SessionInterface $session
   *
   * @return \Symfony\Component\HttpFoundation\Response
   *
   * @Route(
   *   name = "session-get",
   *   path = "session/get"
   * )
   */
  public function get(SessionInterface $session) {
    $q = $session->has('q') ? $session->get('q') : NULL;
    return new Response($q ? "Q is $q" : "Q is not set");

  }

  /**
   * @param \Symfony\Component\HttpFoundation\Session\SessionInterface $session
   * @param \Symfony\Component\HttpFoundation\Request $request
   *
   * @return \Symfony\Component\HttpFoundation\Response
   *
   * @Route(
   *   name = "session-set",
   *   path = "session/set"
   * )
   */
  public function set(SessionInterface $session, Request $request) {
    $q = $request->query->has('q') ? (int) $request->query->get('q') : 0;
    $session->set('q', $q);
    return new Response("Set q to $q");
  }
}