Field Group that is not Empty is Being Hidden

I was able to replicate the issue consistently.

I created the following nested group hierarchy:
- Level 1 (parent of Level 2)
- Level 2 (parent of Level 3)
- Level 3 (contains the body field)

I then reorganized the structure using the Field Group UI:
- Level 3 becomes the top-level group
- It contains Level 2
- Which contains Level 1
- And Level 1 contains the body field

I exported the configuration and noticed. The weight values were correctly updated. However, the field order in the YAML config remained unchanged, still reflecting the original nesting order.

It looks like the Field Group module builds the field group hierarchy based on the order of items in the YAML configuration file, instead of relying solely on the weight and parent_name properties.

This becomes problematic when reversing the hierarchy (e.g., changing a parent into a child or vice versa), because it can impact the visibility of the element

The function field_group_remove_empty_form_groups expects that groups are ordered from parent to child
Added an additional function which orders groups.

Can confirm this issue.
When updating our setup to 4.x a lot of our field groups disappeared.
The MR fixes this mostly, but not entirely. 1 edge case remains for us. (this was working in the previous version)

Consider this setup:

- field_group1
  - field_subgroup1 (render when empty is checked here)

This will not render anything, while I expected it to render fully since the subgroup is marked to render if it is empty (which it is).
It might look like a weird setup, but we use this in combination with the option to render a custom html-tag instead of an actual "group of fields". Also this is an extremely simplified example. Our actual setup contains dozens of nested field groups and a lot of custom classes and javascript processing...

I have tried to fix this locally, but I am not sure this is entirely correct...

If you change this:

      $show_empty_fields = isset($element[$child_name]['#show_empty_fields']) && $element[$child_name]['#show_empty_fields'];
      if ($show_empty_fields) {
        $empty_groups_indication[$child_name] = FALSE;
      }

to this:

      $show_empty_fields = isset($element[$child_name]['#show_empty_fields']) && $element[$child_name]['#show_empty_fields'];
      if ($show_empty_fields) {
        $empty_groups_indication[$child_name] = FALSE;

        // If one of the parents is a group, mark that one as not empty as well.
        if ($element[$child_name]['#group']) {
          $parents = explode('][', $element[$child_name]['#group']);
          if (is_array($parents)) {
            foreach ($parents as $parent_name) {
              if (in_array($parent_name, $groups)) {
                $empty_groups_indication[$parent_name] = FALSE;
              }
            }
          }
        }
      }

it seems to work correctly (for me)...

If we define #9 as a valid config, then the tests needs to be updated to fail on this type of config. Personally I have I never created such a config and my knee jerk reaction to it is, its sort of a hack.

I understand it is a bit weird, but perfectly possible... And, for us at least, it is very very handy feature to be able to put html tags with classes in the form without custom code.

Attached is an updated patch that fixes this use case.

After reading through the issue, I believe that the MR for 3266900 - Hiding empty field groups in form display is not working should resolve the problem. Probably needs a rebase.

The code from 3266900 is based on field_group_remove_empty_display_groups() and also takes show_empty_fields into account.

I have exactly same situation as described in "Problem/Motivation". Still see the problem. The nested fieldgroups dissapear. Why this issue is closed? Where is the fix?

The patch from #3266900: Hiding empty field groups in form display is not working fixes this issue.