Support for printing entity revision

I need to create PDFs of revisions, so I tried #14, but it didn't work for me. Although it alters the controller to accomodate printing revisions from PDFs, it seems to be lacking the {revision_id} path parameter for the entity_print.revision.view and entity_print.revision.view.debug routes.

Also, I couldn't apply the patch via git apply due to a case mismatch in EntityPrintController.php: @TODO should be @todo in the patch. This case change was made back in #3104331 🐛 PHP_CodeSniffer warnings and errors Fixed .

I made the following changes to #14 and got it working for my purposes:

1. added {revision_id} path parameter to the entity_print.revision.view and entity_print.revision.view.debug routes
2. added a missing @param to the viewPrintDebug() document block
3. revised entity_print_entity_view_alter() to add revision_id as a path parameter for the View PDF link.

I'm sure that my revision to entity_print_entity_view_alter() (to alter the View PDF link) is the wrong way to go about this, so consider this patch to be in-progress. It assumes that there's always a revision id, and it works for my specific use case so far. But I'm sure this needs to be improved.

@bengy can I get some feedback on the overall direction of the patch?

Fix fatal error:
Symfony\Component\Routing\Exception\InvalidParameterException: Parameter "revision_id" for route "entity_print.revision.view" must match "[^/]++" ("" given) to generate a corresponding URL. in Drupal\Core\Routing\UrlGenerator->doGenerate() (line 206 of core/lib/Drupal/Core/Routing/UrlGenerator.php).

-        '#access' => $access_manager->checkNamedRoute('entity_print.view', $route_params, NULL, TRUE),
+        '#access' => $access_manager->checkNamedRoute('entity_print.revision.view', $route_params, NULL, TRUE),

With the latest patch we are using access check for the revision page even for the regular non-revision link.
I think it would be cleaner to have two separate paths of control flow.
I am going to prepare an MR.

+   * @param int $revision_id
+   *   The entity revision id.

I think the type needs to be "int|null".
This is what I see a lot in core for parameters with NULL default value.

-  public function viewRedirectDebug($export_type, $entity_type, $entity_id) {
+  public function viewRedirectDebug($export_type, $entity_type, $entity_id, $revision_id = NULL) {
     return $this->redirect('entity_print.view.debug', [
       'export_type' => $export_type,
       'entity_type' => $entity_type,
       'entity_id' => $entity_id,
+      'revision_id' => $revision_id,
     ]);
   }

This seems weird:
The redirect route is only meant for legacy support, so we should not expect this to be called with a revision id.
On the other hand: If we support a revision_id parameter, then we need to conditionally change the route for the redirect to use the revision route.

See also 🐛 Wrong usage of trim() in entity_print_entity_view_alter() Active .
If we solve that, it will conflict with the patches here..

I pushed some what I think are improvements - TBD.
See the individual commit messages.

I should also add tests, but that requires a bit more thinking and searching.

Actually it could be useful to add the revision id or the revision date to the file name of a pdf.

Tested MR following the steps and revision is being printed perfectly.

Something probably that should have simple test coverage.

Don't see any file for moderation so probably could add one to Functional or Kernel folders.