MESSAGE_TAGS ignored in 5.0a1

[James Gillard]

I've been running 5.0a1 off and on with our project to spot issues and have come across my first.

As stated in the title, MESSAGE_TAGS in settings.py is now having no effect for me. I noticed this when the extra classes we define inside settings.py disappeared from the rendered HTML of a message. I tried having a play around with the django test suite to recreate, but I didn't achieve that, so the proof I have is from adding a debug line inside django.contrib.messages.utils.get_level_tags. I stopped at this point, as someone might be able to point out something obvious I've missed that's leading to this.

Here's the debug print I've added:

def get_level_tags():
    """
    Return the message level tags.
    """
    print(getattr(settings, "MESSAGE_TAGS", {}))
    return {
        **constants.DEFAULT_TAGS,
        **getattr(settings, "MESSAGE_TAGS", {}),
    }

Here is what we have inside settings.py:

MESSAGE_TAGS = {
    messages.DEBUG: 'debug alert-info is-info',
    messages.INFO: 'info alert-info is-info',
    messages.SUCCESS: 'success alert-success is-success',
    messages.WARNING: 'warning alert-warning is-warning',
    messages.ERROR: 'error alert-danger is-danger',
}

And here's what I'm seeing when going from 4.2.5 to 5.0a1, and also testing latest main; lines removed for brevity:

✗ pip install Django==4.2.5
✗ ./manage.py runserver
{10: 'debug alert-info is-info', 20: 'info alert-info is-info', 25: 'success alert-success is-success', 30: 'warning alert-warning is-warning', 40: 'error alert-danger is-danger'}
{10: 'debug alert-info is-info', 20: 'info alert-info is-info', 25: 'success alert-success is-success', 30: 'warning alert-warning is-warning', 40: 'error alert-danger is-danger'}
Django version 4.2.5, using settings 'journee.settings'
                                                                                                                                                                                                                                                     
✗ pip install Django==5.0a1
✗ ./manage.py runserver
{}
{}
Django version 5.0a1, using settings 'journee.settings'

✗ pip install git+https://github.com/django/django.git
✗ ./manage.py runserver
{}
{}
Django version 5.1.dev20231023125957, using settings 'journee.settings'

[Mariusz Felisiak]

Thanks for the report! Regression in b7fe36ad37fb18c4bc7932c0aec6ae4f299b9622.

[Mariusz Felisiak]

James, Can you confirm that the following patch fixes this issue for you?

django/contrib/messages/storage/base.py

@@ -1 +1 @@
 from django.conf import settings
 from django.contrib.messages import constants, utils
+from django.utils.functional import SimpleLazyObject
 
-LEVEL_TAGS = utils.get_level_tags()
+LEVEL_TAGS = SimpleLazyObject(utils.get_level_tags)
 
 
 class Message:

[James Gillard]

Hi Mariusz, that does indeed fix it for me!

[Mariusz Felisiak]

​PR

[Natalia <124304+nessita@…>]

In 311718fe:

Fixed #34923 -- Avoided initializing LEVEL_TAGS when importing django.contrib.messages.

Regression in b7fe36ad37fb18c4bc7932c0aec6ae4f299b9622.

Thanks James Gillard for the report.

[Natalia <124304+nessita@…>]

In 00805ff:

[5.0.x] Fixed #34923 -- Avoided initializing LEVEL_TAGS when importing django.contrib.messages.

Regression in b7fe36ad37fb18c4bc7932c0aec6ae4f299b9622.

Thanks James Gillard for the report.

Backport of 311718feb5f1fb9ff794bbac0cda48cfc3410de8 from main