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:
getRequestType()
- Returns the type of the request (
HttpKernelInterface::MASTER_REQUEST
orHttpKernelInterface::SUB_REQUEST
). getKernel()
- Returns the Kernel handling the request.
getRequest()
- Returns the current
Request
being handled.
kernel.request
¶
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 |
kernel.controller
¶
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
$event->setController($controller);
}
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\Bundle\FrameworkBundle\DataCollector\RequestDataCollector |
0 |
kernel.view
¶
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
$event->setResponse($response);
}
See also
Read more on the kernel.view event.
kernel.response
¶
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:
Symfony\Component\HttpKernel\EventListener\ProfilerListener
- Collects data for the current request.
Symfony\Bundle\WebProfilerBundle\EventListener\WebDebugToolbarListener
- Injects the Web Debug Toolbar.
Symfony\Component\HttpKernel\EventListener\ResponseListener
- Fixes the Response
Content-Type
based on the request format. Symfony\Component\HttpKernel\EventListener\EsiListener
- 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\Component\Security\Http\RememberMe\ResponseListener |
0 |
Symfony\Bundle\FrameworkBundle\DataCollector\RequestDataCollector |
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 |
kernel.finish_request
¶
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()) {
return;
}
//Reset the locale of the subrequest to the locale of the parent request
$this->setLocale($parentRequest);
}
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 |
kernel.terminate
¶
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 |
kernel.exception
¶
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
$event->setResponse($response);
// you can alternatively set a new Exception
// $exception = new \Exception('Some special exception');
// $event->setException($exception);
}
Note
Symfony uses the following logic to determine the HTTP status code of the response:
- If
isClientError()
,isServerError()
orisRedirect()
is true, then the status code on yourResponse
object is used; - If the original exception implements
Symfony\Component\HttpKernel\Exception\HttpExceptionInterface
, thengetStatusCode()
is called on the exception and used (the headers fromgetHeaders()
are also added); - If both of the above aren’t true, then a 500 status code is used.
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.