Symfony - using twig in onKernelRequest kills session - php

Question

I have a strange issue in symfony 4.3 (also tested it in 4.2 - same behaviour) - I am using an EventListener to process a request - heres the code:
<?php
namespace App\EventListener;
use App\Entity\Company;
use Doctrine\ORM\EntityManagerInterface;
use Symfony\Component\EventDispatcher\EventSubscriberInterface;
use Symfony\Component\HttpFoundation\Request;
use Symfony\Component\HttpFoundation\Response;
use Symfony\Component\HttpKernel\Event\RequestEvent;
use Symfony\Component\HttpKernel\KernelEvents;
use Twig\Environment;
class ShopListener implements EventSubscriberInterface
{
/** #var EntityManagerInterface */
protected $em;
/** #var Environment */
protected $twig;
public function __construct(EntityManagerInterface $entityManager, Environment $twig)
{
$this->em=$entityManager;
$this->twig=$twig;
}
public function onKernelRequest(RequestEvent $event)
{
if($event->isMasterRequest()===false) {
return;
}
/** #var Request $request */
$request=$event->getRequest();
$subDomain=$request->attributes->get('domain');
if($subDomain===null) {
return;
}
$company=$this->em->getRepository(Company::class)->findOneBy([
'subDomain' => $subDomain,
]);
if($company instanceof Company && $company->shopIsOnline()) {
$request->attributes->set('company',$company);
return;
}
$event->setResponse(
new Response($this->twig->render('page/shop_not_found.html.twig'),404)
);
}
public static function getSubscribedEvents(): array
{
return [
KernelEvents::REQUEST => ['onKernelRequest',0],
];
}
}
After registering that listener, $request->getSession() is always null in my controller (toolbar also notices, that there is no session registered). When deregistering it, the session is there, but the logic in the listener is skipped. I have tried to play around with the priority to ensure, there's no other listener which interferes.
It seems, that already registering that event kills the session (even if onKernelRequest is empty), which is hard to believe.
What am I missing?

Answer 1

Session is created by Symfony\Component\FrameworkBundle\EventListener\SessionListener listener, on kernel.request event too (priority of 128).
This event has a specific behavior: if a listener sets a Response, "the process skips directly to the kernel.response event" to quote the documentation. I would suspect it could causes issues.
Try setting your listener a priority < 0 (I'm getting you tried many), and please checks the order the profiler "Events" section (/_profiler/latest?panel=events).

Answer 2

Found the solution - problem is the injection of the twig-environment in the constructor - without twig everything works as expected. I guess, loading the twig-environment at this stage does something to the session (like loading it too early).
I moved the listener to onKernelController and modified it:
<?php
namespace App\EventListener;
use App\Entity\Company;
use Doctrine\ORM\EntityManagerInterface;
use Symfony\Component\EventDispatcher\EventSubscriberInterface;
use Symfony\Component\HttpFoundation\Request;
use Symfony\Component\HttpFoundation\Response;
use Symfony\Component\HttpKernel\Event\ControllerEvent;
use Symfony\Component\HttpKernel\KernelEvents;
use Twig\Environment;
class ShopListener implements EventSubscriberInterface
{
/** #var EntityManagerInterface */
protected $em;
/** #var Environment */
protected $twig;
public function __construct(EntityManagerInterface $entityManager, Environment $twig)
{
$this->em=$entityManager;
$this->twig=$twig;
}
public function onKernelController(ControllerEvent $controllerEvent)
{
if($controllerEvent->isMasterRequest()===false) {
return;
}
/** #var Request $request */
$request=$controllerEvent->getRequest();
$subDomain = $request->attributes->get('domain');
if($subDomain===null) {
return;
}
$company=$this->em->getRepository(Company::class)->findOneBy([
'subDomain' => $subDomain,
]);
if($company instanceof Company && $company->shopIsOnline()) {
$request->attributes->set('company',$company);
return;
}
$controllerEvent->setController(
function() {
return new Response($this->twig->render('page/shop_not_found.html.twig'),404);
}
);
}
public static function getSubscribedEvents(): array
{
return [
KernelEvents::CONTROLLER => ['onKernelController',128],
];
}
}