Menu link parent can be lost after saving a page as draft and then published

[bberndt-uaz]

Problem/Motivation

An issue was introduced with Drupal 10.2 (Quickstart 2.9.0) which may result in the menu link for a page having its parent item removed, so that the menu item is moved to the top level of the menu. This appears to only occur when using a content moderation workflow.

Describe the bug

The issue may be related to the langcode field for menu links.

1. Menu links that are susceptible to this problem have the langcode und (for "undetermined") in the database.
2. Saving the associated page as a Draft updates the langcode field to en in the menu_link_content, menu_link_content_field_revision, and menu_link_content_revision tables.
3. Finally, when the page is saved again as Published, the langcode field changes to en in menu_link_content_data. This is also when the parent value is set to NULL. (The expanded field is also changed from 0 to NULL.)
4. However, if you set the parent menu link back to what it should be, repeating the previous steps will not cause it to change to NULL again, possibly because the langcode is already en.

I was able to reproduce this issue on a fresh Quickstart build with the demo content installed by manually changing the langcode field for a menu link from en to und in the menu_link_content tables in the database. After saving the page as Draft and then saving it as Published, the parent field for the menu link was set to NULL.

@trackleft noted that this issue may be related to the following Drupal change records and issues:

• New config schema data type: langcode
• Calling \Drupal\menu_link_content\Form\MenuLinkContentForm::_construct() with the $language_manager argument is deprecated
• SchemaCheckTrait::checkConfigSchema() now checks config schema strictly, including validation constraints — affects most tests
• Wrong type of property MenuLinkContent::$link

To Reproduce

Steps to reproduce the behavior:

1. Edit a page in the menu with a parent menu item. In the database, the page's menu item must have a langcode that is different from the menu itself (such as und).
2. Change the state to Draft and save the page.
3. Edit the page again, change the state to Published, and save the page.
4. The parent menu item for the page will change to Main Navigation, thus adding the page to the main nav. No errors are shown.

Proposed resolution

Still to be determined.

Expected behavior

Saving new revisions of a page, regardless of moderation state, should not change the parent menu item for the page.

Additional context

This has been confirmed to affect multiple Arizona Sites.

[bberndt-uaz]

Next steps:

• Determine which Quickstart versions this problem affects
• Determine possible solutions

[bberndt-uaz]

• I tested a Pantheon multidev on Quickstart 2.7.5 (Drupal 10.0) and could not reproduce the issue. Saving a page as draft and then as published resulted in no change to the associated menu link: the langcode remained as und.
• I also tested a multidev that @trackleft set up on Quickstart 2.8.9 (Drupal 10.1) and could not reproduce the issue. Saving a page as draft and then as published resulted in no change to the associated menu link: the langcode remained as und.
• Finally, I tested a multidev that @trackleft set up on Quickstart 2.9.0 (Drupal 10.2.2) and did reproduce the issue. Saving a page as draft and then as published resulted in a change to the associated menu link: the langcode changed from und to en.

[joeparsons]

Possibly related Drupal 10.2.x change record:
Menu link 'Parent link' is limited to the current menu when creating new custom menu links through the UI

[joeparsons]

I think I found the actual 10.2.x change that is causing this problem:
https://git.drupalcode.org/project/drupal/-/commit/91acedade93894c41d3aef75a6c7511a9db6be29

Basically code was added to the core menu_ui module that ensures the langcode of menu links matches the associated node's langcode when nodes are saved.

Drupal.org issue associated with the change:
https://www.drupal.org/project/drupal/issues/2904899

[joeparsons]

My working theory after looking through a bunch of issues and code history on Drupal.org is:

• This is likely only affecting sites with menu links that were migrated using our Quickstart migration(s)
• The change that was included in 10.2 that updates the menu_link_content langcode value if it doesn't match the associated node's langcode value makes discrepancies between between langcode values for parent/child menu links much more likely
• When those discrepancies exist, the content moderation issue that resets the parent value of the menu link seems to occur when publishing a draft revision of the associated node

I verified that:

• The schema for menu_links in D7 did not include a language/langcode value by default (see system.install#L1272-1456)
• The langcode value for menu_links migrated with az_migration's az_menu_linksmigration is set to und by default (see az_menu_links.yml#L23-L26)
• New menu links and content nodes created on Quickstart 2 sites have a langcode value of en by default (unless the site has configured a different default language configured in system.site default_langcode?)
• Creating a draft revision on a newly created page + menu link and then resaving to publish the revision does not seem cause the content_revision issue to occur that resets the menu link parent value

[bberndt-uaz]

Next steps: Create a PR that adds a database update to change menu links with the und langcode to have the site's default langcode instead. The PR can also update the az_menu_links migration. We will need to test the database update on a site with multiple languages. For the migration, we should consider that the source site and destination site may not have the same languages.