Improve linking to md version of an entity

Thanks for the great suggestion, mxr576! I already have this implemented in a local branch of the module, though I haven’t been able to push it yet.

@Christophweber, what mxr576 is suggesting is essentially adding a new Link Template to entities marked as supported for Markdown conversion.

Here’s the official documentation on how to do it: Link Relation Types and Link Templates →

The implementation is straightforward and looks like this:

/**
 * Implements hook_entity_type_alter().
 *
 * Adds a 'markdownify' link template to supported entity types.
 */
function markdownify_entity_type_alter(array &$entity_types): void {
  /** @var \Drupal\Core\Entity\EntityTypeInterface[] $entity_types */
  $validator = \Drupal::service('markdownify.supported_entity_types.validator');

  foreach ($validator->getSupportedEntityTypes() as $entity_type_id) {
    if (!isset($entity_types[$entity_type_id])) {
      continue;
    }

    $entity_type = $entity_types[$entity_type_id];
    if (!$entity_type instanceof EntityTypeInterface) {
      continue;
    }

    // Add 'markdownify' link template based on the canonical path.
    if ($entity_type->hasLinkTemplate('canonical')) {
      $canonical_path = $entity_type->getLinkTemplate('canonical');
      $entity_type->setLinkTemplate('markdownify', $canonical_path . '.md');
    }
  }
}

The reason I haven’t pushed this contribution yet is that I’m uncertain about the name of the link template. In my implementation, I named it 'markdownify', so people can get the Markdown URL using code like this:

$markdown_url = $entity->toUrl('markdownify')->setAbsolute(TRUE)->toString();

However, in mxr576's example, the name is 'canonical-md', which means the URL would be retrieved like this:

$markdown_url = $entity->toUrl('canonical-md')->setAbsolute(TRUE)->toString();

Do you have any preferences for the naming convention? Let me know, and I’ll push a merge request with the changes.

Thanks!

Since it is code from this module making the adjustment to the link, and there could presumably be other modules doing the same or similar, let's go with:
$markdown_url = $entity->toUrl('markdownify')->setAbsolute(TRUE)->toString();