Add workspace ID to preview

[Decipher]

Package

I’m not sure

Describe the feature request

In the case that workspaces is enabled, the frontend needs the workspace ID so that it can be used to ensure workspace specific entities are returned.

Describe the solution you'd like

Add workspace query parameter to the preview.

Describe alternatives you've considered

Additional context

In this implementation, the workspace ID is being sent back as a header and a Drupal EventSubscriber is using the header to set the active workspace for a GraphQL session.,

[khalidbouhouch77]

Hello @Decipher
I was working on something similar. I created an event subscriber that retrieves the workspace query parameter, then loads the workspace and sets it as active.
The problem is that we also need to switch the user to one that has permission to view unpublished content (in my case, I was testing with an admin account).

public function onKernelRequest(RequestEvent $event) {
    $request = $event->getRequest();
    $workspace_id = $request->query->get('workspace', NULL);

    if (!$workspace_id) {
      return;
    }

    $workspace = \Drupal::entityTypeManager()
      ->getStorage('workspace')
      ->load($workspace_id);
    if (!$workspace instanceof WorkspaceInterface) {
      return;
    }

    try {
      $accountSwitcher = \Drupal::service('account_switcher');
      $accountSwitcher->switchTo(new UserSession(['uid' => 1]));
      \Drupal::service('workspaces.manager')->setActiveWorkspace($workspace);
    }
    catch (\Exception $e) {
      \Drupal::logger('workspace_switcher')
        ->error('Failed to set JSON API context: @message', ['@message' => $e->getMessage()]);
    }
  }

[bojanbogdanovic]

This seems like an edge case to me, and I can imagine that similar cases could arise with other modules. I think we should move the getPreviewUrlForEntity(), getLiveUrlForEntity(), and buildRevalidateUrl() methods into a service. That way, the community could decorate or replace the service to modify the behavior if needed.