Fix bulk_update() on I18n_JSON fields for homogenous values #10618

[jacobtylerwalls]

Types of changes

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Description of Change

Before, there was silent data loss when using bulk_update() on I18n_JSON fields such as node, datatype, widget, plugin configs.

Now, we at least allow bulk_updates to homogenous values. Heterogenous values (not yet supported) throw an error to prevent a silent failure.

The situation may improve in Django 5.1 if someone submits a PR with the patch identified in this ticket. Maybe that someone is one of us? :D

Issues Solved

Closes #10618

Opened a followup #10619 for the issue demo'd in the skipped test.

Checklist

• Unit tests pass locally with my changes
• I have added tests that prove my fix is effective or that my feature works
• I have added necessary documentation (if appropriate)

Ticket Background

• Sponsored by: GCI
• Found by: @jacobtylerwalls
• Tested by: @jacobtylerwalls

[apeters]

looks good to me. How should we remind ourselves to remove this code once we move to Django 5.1? A deprecation warning?

[jacobtylerwalls]

Good call. I guess I'm hopeful it will be fixed in 5.1, but we don't know.

I can take the test that currently has an expected failure decorator and make it more specific to assert against NotImplementedError, and then if the underlying issue of sending Cast objects is fixed, that test will start failing because we won't reach that code block, and I'll leave a comment telling future us what to do.

[jacobtylerwalls]

Retargeted 7.6, as this isn't really important enough to go back to 7.5, just adding safety for development.

[apeters]

looks good