In my Drupal 9 site with CKEditor 4 and I have created "media gallery" media type, which displays set of images (using slideshow module). So, when I click "insert media" CKEditor button for tool bar I have media selector popup, I can select and insert media gallery and that works well.

Only problem is that when media is inserted, that AJAX call is cached. So if I for example edit gallery, add another image or remove one and I go to insert that gallery in CKEditor I get old gallery, in state before my recent editing.

When I look at entity media it self it gets updated immediately, but AJAX call CKEditor makes is cached.

How can I disable that caching? Or force cache rebuild when gallery is saved?


I figured out that at: web/core/modules/media/src/Controller/MediaFilterController.php preview method is setting MaxAge value to 300 (5 minutes).

    // Note that we intentionally do not use:
// - \Drupal\Core\Cache\CacheableResponse because caching it on the server
//   side is wasteful, hence there is no need for cacheability metadata.
// - \Drupal\Core\Render\HtmlResponse because there is no need for
//   attachments nor cacheability metadata.
return (new Response($html, 200, $headers))
  // Do not allow any intermediary to cache the response, only the end user.
  // Allow the end user to cache it for up to 5 minutes.

If I change parameter to 0 it starts working well. Now, is there a reason why this caching is needed and what would be the optimal way to solve this issue? I saw that this code has long history, yet since it was a separate module:


1 Answer 1


Solved this by overriding the class and route that was using original's class method. So, I have route subscriber defined like:

    class: Drupal\my_module\Routing\RouteSubscriber
      - { name: event_subscriber }

Then I have route subscriber it self like:


namespace Drupal\my_module\Routing;

use Drupal\Core\Routing\RouteSubscriberBase;
use Symfony\Component\Routing\RouteCollection;

 * Listens to the dynamic route events.
class RouteSubscriber extends RouteSubscriberBase {

   * {@inheritdoc}
  protected function alterRoutes(RouteCollection $collection) {
    // Overriding default MaxEge (5 minutes) value of API response.
    if ($route = $collection->get('media.filter.preview')) {
      $route->setDefault('_controller', '\Drupal\my_module\Controller\MyModuleMediaFilterController::preview');


And finally I have class override:


namespace Drupal\my_module\Controller;

use Drupal\filter\FilterFormatInterface;
use Drupal\media\Controller\MediaFilterController;
use Symfony\Component\HttpFoundation\Request;

 * MediaFilterController override.
class MyModuleMediaFilterController extends MediaFilterController {

   * Returns an HTML response containing a preview of the text after filtering.
  public function preview(Request $request, FilterFormatInterface $filter_format) {
    // Overriding default MaxAge value of 300 (5 minutes).
    return parent::preview($request, $filter_format)->setMaxAge(0);


Hopefully this will help someone and save some time. Maybe some condition can be added to preview override, like remove caching only for back-end or similar.

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