Ability to filter terms by "virtual" parent

Thanks for taking the time to report this! 🙏

I think that's a reasonable expectation, but it would be a new feature. This has never been supported.

This is not yet passing tests, but something like this is the test coverage we'd want, and which this feature is asking to pass.

+1

I think #3025372: [regression] Impossible to filter for resources with an empty relationship object in JSON:API 2.x is related. At least conceptually, but potentially also in terms of patch.

#3025372: [regression] Impossible to filter for resources with an empty relationship object in JSON:API 2.x just landed! Let's push this forward now.

Hello, guys!

Correct me if I am wrong, but I think we "done-done" here just because the other issue (#3025372: [regression] Impossible to filter for resources with an empty relationship object in JSON:API 2.x) has been resolved.

/jsonapi/taxonomy_term/campaign_goal?filter[alex][condition][path]=parent.id&filter[alex][condition][operator]=IS NULL
yields the correct result to me on a 8.9.3 core, i.e. to fetch the top-most terms you just query for such terms whose parent is NULL.

I think to make this issue entirely resolved, the only thing I would propose additionally is to update the docs pages related to the to state the exact way you can filter things.

I am going to correct you :)

This works when you are logged in, in Drupal 9.4.5. When the request is done by an anonymous user, it's empty.

EDIT : We found a way to make it work. You need to filter by parent.id and leave the value field empty.