Duplicate content when using field group

[markabur]

I recently updated paragraphs and field_group, and now I'm seeing fields that are inside of a field group in a paragraph item printed twice -- once inside of the field group and once outside of the field group.

Here is the display for my paragraphs item:

Here is how it outputs:

Important: this only happens if I have overridden paragraphs-item.tpl.php in my custom theme. The template doesn't need to have any changes, it just needs to exist.

This is coming up now for me because of this recent change in field_group.module:

  // Support for Entity Plus API.
  if (isset($theme_registry['entity_plus'])) {
    $entities[] = 'entity_plus';
  }

If I comment that out, then the fields are not duplicated.

However, there is another fix. I haven't done any tracing to figure out why this works, but the problem also gets fixed If I comment out this line in ParagraphsItemEntityController:

$build['#theme'] = 'paragraphs_item';

[markabur]

Oh, the reason this works is because it prevents template_preprocess_paragraphs_item() from getting called, so it's not a good solution, but hopefully it's a clue.

[argiepiano]

This may be related to a D8 bug, and patch: https://www.drupal.org/project/paragraphs/issues/2907094

Probably this patch was never made backward-compatible with D7, and therefore doesn't exist in Backdrop.

[argiepiano]

The patch is very simple - it's an if statement to find out if field_group is enabled, and then adds a pre_render callback from field_group.

[markabur]

If I am reading the issue correctly, they are talking about changing #pre_render to #process. Since Backdrop got rid of the whole #process layer, that patch won't have any effect.

Here is my hackish fix for now. It's not ideal because it makes field_group_build_entity_groups() run a second time on the same content.

function mytheme_preprocess_paragraphs_item(&$vars) {
  // Rebuild $vars['content'] so field_group fields don't print twice. This is
  // necessary because template_preprocess_paragraphs_item() runs after
  // field_group_build_entity_groups() when there is a paragraphs-item.tpl.php
  // in the theme. See theme.inc line 1132.
  field_group_build_entity_groups($vars, 'paragraphs_item');
}

It would be helpful if Backdrop had #process, because field_group_build_entity_groups() really needs to run after template_preprocess_paragraphs_item().

[argiepiano]

No, I'm referring to this simple patch that uses #pre_render. https://git.drupalcode.org/project/paragraphs/-/commit/c8387b322e780dcb53d04b548e59244af4656b6c

Again, I haven't looked at this in depth. I'm just pointing out the simple patch.

EDIT: Oh, OK, I see the patch also uses #process.

[markabur]

Thanks, yeah, it uses both, but I think only one of them will run depending on which version of field_group is installed.

Anyway, it looks like field_group for Backdrop already does the same thing?

function field_group_field_attach_form($entity_type, $entity, &$form, &$form_state, $langcode) {
  [...]
  field_group_attach_groups($form, 'form', $form_state);
  $form['#pre_render'][] = 'field_group_form_pre_render';
}

[markabur]

This is related to #248. It's kind of complicated so it will take some time to write up. I will have a PR too.