AutocompleteSelectMultipleFilter compatibility issue with Django 4.2

[omarraafat14]

What version of Unfold are you using?
0.57.0

What version of Django are you using?
4.2

What browser are you using?
Edge 136.0.3240.92

Did you checked changelog/commit history, if the bug is not already fixed?
Yes

Did you searched other issues, if the bug is not already fixed?
Yes

Did you checked documentation?
Yes

Are you able to replicate the bug in the demo site?
No, As demo site using Django 5 while I am using Django 4.2

Repository with reproduced bug
https://github.com/omarraafat14/miran-search-api

Describe your issue

The AutocompleteSelectMultipleFilter from unfold.contrib.filters throws an "Enter a list of values" error when used with Django 4.2, while it works correctly with Django 5.x.

Steps to reproduce:

1. Set up Django 4.2 project with Unfold
2. Create a model with ManyToManyField relationships
3. Configure admin with AutocompleteSelectMultipleFilter
4. Try to use the filter in admin interface

Expected behavior:
The autocomplete filter should work as documented, allowing multiple selection of related objects.

Actual behavior:
Error message "Enter a list of values" appears when trying to use the filter.

Additional context:

• The same code works perfectly with Django 5.x
• Regular Django autocomplete fields work fine in Django 4.2
• Only the Unfold AutocompleteSelectMultipleFilter is affected
• AutocompleteSelectFilter (single selection) may have the same issue

[justinqian42]

@sezginacer unfortunately the merged PR #1042 (comment) breaks compatibility with Django 4.2 LTS (supported until April 2026).

I understand the issue you were facing with multiple values for the same parameter name.

• Unfortunately, in Django 4.2’s ChangeList there’s no filter_params, but only params, which swallows multiple values: https://github.com/django/django/blob/stable/4.2.x/django/contrib/admin/views/main.py#L112

• In Django 5.x’s ChangeList there’s filter_params: https://github.com/django/django/blob/240421c7c4c81fe5df26274b807266bd4ca73d7f/django/contrib/admin/views/main.py#L128

Options

• One option is to restore functionality for Django 4.2 with a fallback to params if filter_params is unavailable. But that will only restore the previous behavior for Django 4.2 without support for multiple values.
• Alternatively, we could introduce ChangeList for unfold and add filter_params which either falls back to the super classes filter_params or the backported code for Django 4.2.
• Do you have other ideas? E.g. is there a better way of providing multiple values for the same param? ?status=2&status=3 ain’t best practise.

Originally posted by @dbartenstein in #999

[justinqian42]

The issue seems to persist in the latest unfold version.
Try to upgrade to Django 5.0 or onwards.