Allow AjaxResponse to be altered

> I'm also seeing in latest -dev that ActionLinkController::generateResponse was made private (was protected in -alpha3), which means that the workaround in the initial request is no longer possible.

I'd like to see that reverted, feel free to do that here. private shouldn't be used in Drupal unless there's a reason for it. Default is protected. There might be other reasons where overriding the controller would be easier than a response subscriber.

It's still a controller and not really covered by BC, you can do it but your code might break. that's fine.

is here any document how to use this feature？
I want to perform additional js actions after a flag is triggered， I could not found any document about it.
For Drupal 7 flag module, there are a detail document about this.

This patch applies and works for me.
+1

Thanks

In case anyone is interested, with this patch in place I was able to make a submodule that replaces flags default feedback messages with noty.js style messages.

see: https://github.com/lozeone/drupal8_noty and https://ned.im/noty/#/
take a look at the FlagAjaxResponseSubscriber.php file to see how to add your own ajax commands to the event.

Create event for alter response on action.

Hi, I can confirm the patch in #8 applies without issues and it allows to subscribe to a FlagEvents.

My current set up is
Drupal 9.1.10
Flag 8.x-4.0-beta2

After applying the patch I was able to subscribe to a FlagEvents following instructions in here https://www.drupal.org/docs/creating-custom-modules/subscribe-to-and-dis....

For reference, my EventSubscriber class looks like

namespace Drupal\my_module\EventSubscriber;


use Drupal\flag\Event\FlagEvents;
use Drupal\flag\Event\FlagResponseEvent;
use Symfony\Component\EventDispatcher\EventSubscriberInterface;

/**
 * Alter a Flag Ajax Response.
 */
class FlagAjaxResponseSubscriber implements EventSubscriberInterface{

  /**
   * {@inheritdoc}
   */
  public static function getSubscribedEvents() {
    return [
      FlagEvents::RESPONSE => 'onResponse',
    ];
  }

  /**
   * Allows us to alter the Ajax response from a flag.
   *
   * @param \Symfony\Component\HttpKernel\Event\FilterResponseEvent $event
   *   The event process.
   */
  public function onResponse(FlagResponseEvent $event) {
    $response = $event->getResponse();
    $action_type = $event->getActionType(); // either 'flag' or 'unflag'

    if ($response instanceof \Drupal\Core\Ajax\AjaxResponse) {
      if ($action_type == 'flag') {
        // Do something.
      }
      else {
        // Do something else.
      }
    }
  }

}

Yes, the patch in #8 works great! Thanks, this was just what i needed! :-D

Thanks! RTBC+1

The patch at #8 does not work on Drupal 10.1 which has a newer version of symfony. On Symfony 4.3+ the dispatch method has been changed
from
public function dispatch($eventName, Event $event = null);
to
public function dispatch(object $event, ?string $eventName = null): object;

This new patch addresses that issue. It's a one line change.

The patch in #13 works correctly for drupal 10.1+.
I've been using it in production for a while now, with no issues. Thanks!

Needs reroll to MR, needs tests how it works

I've moved the code from the patch in #13 to the branch and created a PR.

It still needs testing though.

Still needs tests

Cherry picked the commit to open a new MR for 5x, test needed.

Added a Kernel test that test the response can be altered. Ready for review.