How to retrieve the debug token on exception?

Question

I have written my own ExceptionController and want to inject the debug token as part of the output.
I had a look on the WebProfilerToolbarListener, which is similar to my case but it seems that the exception/error response has another lifecycle.

The ProfilerCollector is always called after my listener, which is on the response event.
My Listener needs to be called after the ProfilerCollector.

How can I achieve it?

Answer 1

I have tried to use different priorities, but it seems that you need to clear the cache completly. It isn't sufficient to reload the page in development mode.

After changing the priority to -150 like below it works.

profiler_link_listener:
    class:Nerdhive\TheNetwork\TwigBundle\EventListener\ProfilerLinkListener
    priority: -150
    tags:
        - { name: kernel.event_listener, event: kernel.response, method: onKernelResponse }

You can retrieve the debug token like below:

public function onKernelResponse(FilterResponseEvent $event)
{
    $response = $event->getResponse();
    $token = $response->headers->get('X-Debug-Token');
    // Do here your stuff
}

In general -129 should also work regarding the WebDebugToolbarListener or documentation:

public static function getSubscribedEvents()
{
    return array(
        KernelEvents::RESPONSE => array('onKernelResponse', -128),
    );
}