Allow to use referenced entity fields as a caption source

Right now you can't use media tokens when using photoswipe field formatter on node for media entity reference field. That's because this code $entity_type = $imageDTO->getEntity()->getEntityTypeId();(source) returns a host entity (node) when formatter being called from node rendering.
I have a similar situation but we are using paragraph for storing image with additional data. We're also using custom caption field but inside paragraph. I modified https://git.drupalcode.org/project/photoswipe/-/blob/5.x/modules/photosw... by this:

case 'custom':
        $entity_type = $imageDTO->getEntity()->getEntityTypeId();
        $entity = $imageDTO->getEntity();
        $token = $thirdPartySettings['photoswipe_dynamic_caption']['photoswipe_caption_custom'];

        // Try to extract parent entity type from token.
        $token_parts = explode(':', str_replace(['[', ']'], '', $token));
        $token_entity_type = $token_parts[0] ?? NULL;
        // Let's use parent entity for token generation.
        if (count($token_parts) > 1) {
          $entity_type = $token_entity_type;
          $entity = $imageDTO->getItem()->getParent()->getEntity();
        }

        $caption = \Drupal::service('token')->replace($token,
          [
            $entity_type => $entity,
            'file' => $imageDTO->getItem(),
          ],
          [
            'clear' => TRUE,
            'langcode' => \Drupal::service('language_manager')->getCurrentLanguage()->getId(),
          ]
        );
        break;

I agree it would be helpful to add related / parent entity tokens, but I dislike this approach:

        // Try to extract parent entity type from token.
        $token_parts = explode(':', str_replace(['[', ']'], '', $token));
        $token_entity_type = $token_parts[0] ?? NULL;

Any other ideas how to add the references token more cleanly? Has this perhaps already been solved somewhere else?

@anybody see here: https://www.drupal.org/project/photoswipe/issues/3024243#comment-15804453

I encountered a similar issue. We also have a separate 'field_caption' field on 'Media Image', and this field is n/a in the 'PhotoSwipe-Caption' dropdown menu. Using the token [media:field_caption] does not work either.

The formatter is Photoswipe Responsive.

@grevil: Could you please have a look in the next days?

IMO, this issue shouldn't be about improving the token compatibility, but rather be a feature request to add compatibility to use the referenced entity fields as a caption source.

I also added a test. Please review!

@grevil LGTM, but as the original request asked for a token reference support, we should either add that here too (using a Drupal typical token name like in similar reference cases) or at least add a follow-up.

RTBC'd by thomas.frobieter. Code-wise this is fine for me. Please note #14! (Follow-up for reference token)

@grevil LGTM, but as the original request asked for a token reference support

Not quite. The original request was, whether there is a way to use a field on the referenced entity (in this case media) as caption source. Their approach was, to use tokens, we simply provided a different approach to fix this issue!

Nevertheless, I created a follow-up issue here: #3548372: Photoswipe Caption: Allow to use referenced entity's tokens as caption source.

Thx, yes the token approach would also be very nice and flexible, but should be implemented by someone who needs it. Thanks!