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Symfony Framework Events

Symfony Framework Events

When the Symfony Framework (or anything using the Symfony\Component\HttpKernel\HttpKernel) handles a request, a few core events are dispatched so that you can add listeners throughout the process. These are called the “kernel events”. For a larger explanation, see The HttpKernel Component.

Kernel Events

Each event dispatched by the kernel is a subclass of Symfony\Component\HttpKernel\Event\KernelEvent. This means that each event has access to the following information:

Returns the type of the request (HttpKernelInterface::MASTER_REQUEST or HttpKernelInterface::SUB_REQUEST).
Returns the Kernel handling the request.
Returns the current Request being handled.


Event Class: Symfony\Component\HttpKernel\Event\GetResponseEvent

This event is dispatched very early in Symfony, before the controller is determined.

See also

Read more on the kernel.request event.

These are the built-in Symfony listeners registered to this event:

Listener Class Name Priority
Symfony\Component\HttpKernel\EventListener\ProfilerListener 1024
Symfony\Bundle\FrameworkBundle\EventListener\TestSessionListener 192
Symfony\Bundle\FrameworkBundle\EventListener\SessionListener 128
Symfony\Component\HttpKernel\EventListener\RouterListener 32
Symfony\Component\HttpKernel\EventListener\LocaleListener 16
Symfony\Component\Security\Http\Firewall 8


Event Class: Symfony\Component\HttpKernel\Event\FilterControllerEvent

This event can be an entry point used to modify the controller that should be executed:

use Symfony\Component\HttpKernel\Event\FilterControllerEvent;

public function onKernelController(FilterControllerEvent $event)
    $controller = $event->getController();
    // ...

    // the controller can be changed to any PHP callable

See also

Read more on the kernel.controller event.

This is the built-in Symfony listener related to this event:

Listener Class Name Priority
Symfony\Component\HttpKernel\DataCollector\RequestDataCollector 0


Event Class: Symfony\Component\HttpKernel\Event\GetResponseForControllerResultEvent

This event is not used by the FrameworkBundle, but it can be used to implement a view sub-system. This event is called only if the Controller does not return a Response object. The purpose of the event is to allow some other return value to be converted into a Response.

The value returned by the Controller is accessible via the getControllerResult method:

use Symfony\Component\HttpKernel\Event\GetResponseForControllerResultEvent;
use Symfony\Component\HttpFoundation\Response;

public function onKernelView(GetResponseForControllerResultEvent $event)
    $val = $event->getControllerResult();
    $response = new Response();

    // ... somehow customize the Response from the return value


See also

Read more on the kernel.view event.


Event Class: Symfony\Component\HttpKernel\Event\FilterResponseEvent

The purpose of this event is to allow other systems to modify or replace the Response object after its creation:

public function onKernelResponse(FilterResponseEvent $event)
    $response = $event->getResponse();

    // ... modify the response object

The FrameworkBundle registers several listeners:

Collects data for the current request.
Injects the Web Debug Toolbar.
Fixes the Response Content-Type based on the request format.
Adds a Surrogate-Control HTTP header when the Response needs to be parsed for ESI tags.

See also

Read more on the kernel.response event.

These are the built-in Symfony listeners registered to this event:

Listener Class Name Priority
Symfony\Component\HttpKernel\EventListener\EsiListener 0
Symfony\Component\HttpKernel\EventListener\ResponseListener 0
Symfony\Bundle\SecurityBundle\EventListener\ResponseListener 0
Symfony\Component\HttpKernel\EventListener\ProfilerListener -100
Symfony\Bundle\FrameworkBundle\EventListener\TestSessionListener -128
Symfony\Bundle\WebProfilerBundle\EventListener\WebDebugToolbarListener -128
Symfony\Component\HttpKernel\EventListener\StreamedResponseListener -1024


Event Class: Symfony\Component\HttpKernel\Event\FinishRequestEvent

The purpose of this event is to allow you to reset the global and environmental state of the application after a sub-request has finished (for example, the translator listener resets the translator’s locale to the one of the parent request):

public function onKernelFinishRequest(FinishRequestEvent $event)
    if (null === $parentRequest = $this->requestStack->getParentRequest()) {

    //Reset the locale of the subrequest to the locale of the parent request

These are the built-in Symfony listeners related to this event:

Listener Class Name Priority
Symfony\Component\HttpKernel\EventListener\LocaleListener 0
Symfony\Component\HttpKernel\EventListener\TranslatorListener 0
Symfony\Component\HttpKernel\EventListener\RouterListener 0
Symfony\Component\Security\Http\Firewall 0


Event Class: Symfony\Component\HttpKernel\Event\PostResponseEvent

The purpose of this event is to perform tasks after the response was already served to the client.

See also

Read more on the kernel.terminate event.

This is the built-in Symfony listener related to this event:

Listener Class Name Priority
EmailSenderListener 0


Event Class: Symfony\Component\HttpKernel\Event\GetResponseForExceptionEvent

The TwigBundle registers an Symfony\Component\HttpKernel\EventListener\ExceptionListener that forwards the Request to a given controller defined by the exception_listener.controller parameter.

A listener on this event can create and set a Response object, create and set a new Exception object, or do nothing:

use Symfony\Component\HttpKernel\Event\GetResponseForExceptionEvent;
use Symfony\Component\HttpFoundation\Response;

public function onKernelException(GetResponseForExceptionEvent $event)
    $exception = $event->getException();
    $response = new Response();
    // setup the Response object based on the caught exception

    // you can alternatively set a new Exception
    // $exception = new \Exception('Some special exception');
    // $event->setException($exception);


As Symfony ensures that the Response status code is set to the most appropriate one depending on the exception, setting the status on the response won’t work. If you want to overwrite the status code (which you should not without a good reason), set the X-Status-Code header:

$response = new Response(
    404, // this status code will be ignored
        'X-Status-Code' => 200 // this status code will actually be sent to the client

See also

Read more on the kernel.exception event.

These are the built-in Symfony listeners registered to this event:

Listener Class Name Priority
Symfony\Component\HttpKernel\EventListener\ProfilerListener 0
Symfony\Component\HttpKernel\EventListener\ExceptionListener -128

This work, including the code samples, is licensed under a Creative Commons BY-SA 3.0 license.