Make link title editable / add token support / more options

I took a pass at this using the approach of adding a theme function that receives the media object.
This makes it possible for site owners to add in whatever variables they like from the media object.

I could attempt to add the code for some of the field formatter options as well.

One reason I did not is that it would clash with settings changes pending in this issue: https://www.drupal.org/project/media_entity_download/issues/3008834 while a theme function can be added independently.

I also realised that I forgot to add cache tags to the theme function. I have update the patch to include them.

The markup test is a good idea but would have to exist before this patch is applied therefore it would need to be a separate issue, merged first.

Patch super useful for document downloads.

{{ link|merge({'#title': media_entity.name.value }) }} in a twig and happy!

Sorry, I realise that I missed adding the staged files in the patch in #5. Here is one with the cache tags added that has all the files.

Needs a reroll and a complete, combined patch.

Rerolled and combined #5 and #7. Created a merge request https://git.drupalcode.org/project/media_entity_download/-/merge_requests/1 and attached a patch file for review.

This is working like a charm for me.

#11 works great on 8.x-2.1, thanks @capysara!
For reference I altered the button like this:

{% set download_title %}
  <span class="material-icons" focusable="false" aria-hidden="true">download</span>Download {{ media_entity.name.value }}
{% endset %}

{% block media_entity_download_link %}
  {{ link(download_title, url, { 'class':['button', 'button--dark', 'media-download']}) }}
{% endblock media_entity_download_link %}

I'm unsure if this is off-topic, but the default media formatter for "documents" also prints the filetype and filesize alongside the title, eg. Media name (PDF, 12.3KB).
I added here a patch that adds those 2 variables in the template, since it could be a fairly common requirement (and also a good practice).

For reference: alternatively, this can also be done in the in your .theme file using a preprocess hook, without my attached patch:

/**
 * Implements hook_preprocess_HOOK().
 *
 * HOOK: 'media_entity_download_link'.
 *
 * Provides the filetype and the formatted filesize for the media entity download link.
 */
function mytheme_preprocess_media_entity_download_link(array &$variables): void {
  if (!empty($media = $variables['media_entity']) && $media instanceof MediaInterface) {
    $file_field = $media->getSource()->getSourceFieldDefinition($media->get('bundle')->entity);
    if ($file_field && $media->hasField($file_field->getName()) && $media->get($file_field->getName())->entity instanceof FileInterface) {
      $file_entity = $media->get($file_field->getName())->entity;
      $variables['filesize'] = format_size($file_entity->getSize());
      $variables['filetype'] = strtoupper(pathinfo($file_entity->getFilename(), PATHINFO_EXTENSION));
    }
  }
}

The patch at 11 works fine.
The patch at 15 is really helpful, but not necessarily relevant to this issue, and should be added to a fresh issue as a separate feature request.

Patch #11 is working well. I'm using Drupal 10.2.5 at the moment.

Steps taken:

• Make sure download link is set for Document under /admin/structure/media/manage/document/display. And for my use case: add Name to the form display
• Add patch #11 to composer.patches.json and run composer install
• Copy the media-entity-download-link.html.twig template from /modules/contrib/media_entity_download/templates to the theme folder
• Apply the changes in the markup. I'm using the Name field as the link text. This makes the most sense (the description field is not available anyway). This code inside the Twig block: {{ link|merge({'#title': media_entity.name.value }) }}