WorkspaceSubscriber service parameter $workspaceAssociation must be optional

Keshav Patel → made their first commit to this issue’s fork.

@Keshev Patel, thanks for the MR. Can you please explain why you opted for the required parameter solution? This is helpful for other people to review your MR.

Yes an explanation is needed. Also a test case

In the original service definition, the second argument is specified as @?workspaces.association. The ? indicates that this argument is optional, meaning that the WorkspaceSubscriber class can accept either the workspaces.association service or no service at all.

In the modified service definition, the optional operator ? has been removed from the second argument. This means that the WorkspaceSubscriber class now explicitly expects the @workspaces.association service as a required argument.

Purpose of the Change:
The modification aligns the service definition with the actual constructor requirements of the WorkspaceSubscriber class. By removing the optional operator, the service definition accurately reflects that the WorkspaceSubscriber class expects the @workspaces.association service to be provided during instantiation.

After apply the patch from merge request !5978 I have that error.
The service "content_moderation.workspace_subscriber" has a dependency on a non-existent service "workspaces.association".

In the service definition, the workspaces.association service must be marked as optional because it might not exist (for example when the Workspaces module is not enabled).

Note that this is not a bug because \Drupal\content_moderation\EventSubscriber\WorkspaceSubscriber is an event subscriber class, and it shouldn't be instantiated unless it needs to react to the WorkspacePrePublishEvent event, which is only invoked when the Workspaces module is enabled. If some other module instantiates it.. well, it shouldn't :)

If we want to make a change in core though, we need to mark the argument as optional in \Drupal\content_moderation\EventSubscriber\WorkspaceSubscriber::__construct(). Updated the issue summary to reflect that.

stefan.korn → made their first commit to this issue’s fork.

Thanks for the explanation.

As mentioned in 🐛 Workspaces can't be published from the command line Fixed devel quits with WSOD on "Event info". And yes, this is happening if the content moderation module is installed and the workspaces module is not.

Basically

Drupal::service('event_dispatcher')->getListeners();

is failing then.

It seems to me that getListeners() without event argument is a valid call, therefore I am wondering if this should really end in error here (no exceptions for the method pointing in that direction either) even if the workspaces module is not installed.

And the difference between service definition (optional) and implementation (required) does also seem not really straightforward.

I have amended the MR to make the change in the implementation and not the service defintion.

Ok, let's do this, the change is harmless and allows the class to be instantiated :)

Committed/pushed to 11.x and cherry-picked to 10.3.x, thanks!