Customizing Django admin fieldsets without fearing forgotten fields

When defining fieldsets on Django modeladmin classes I always worry that I forget updating the fieldsets later when adding or removing new model fields, and not without reason: It has already happened to me several times. Forgetting to remove fields is mostly fine because system checks will complain about it, forgetting to add fields may be real bad. A recent example was a crashing website because a required field was missing from the admin and therefore was left empty when creating new instances!

I have now published another Django package which solves this by adding support for specifying the special "__remaining__" field in a fieldsets definition. The "__remaining__" placeholder is automatically replaced by all model fields which haven’t been explicitly added already or added to exclude¹.

Here’s a short example for a modeladmin definition using django-auto-admin-fieldsets:

from django.contrib import admin
from django_auto_admin_fieldsets.admin import AutoFieldsetsModelAdmin
from app import models

@admin.register(models.MyModel)
class MyModelAdmin(AutoFieldsetsModelAdmin):
    # Define fieldsets as usual with a placeholder
    fieldsets = [
        ("Basic Information", {"fields": ["title", "slug"]}),
        ("Content", {"fields": ["__remaining__"]}),
    ]

I have used Claude Code a lot for the code and the package, and as always, I had to fix bugs and oversights. I hope it didn’t regurgitate the code of an existing package – I searched for an existing solution first but didn’t find any.

The package is available on PyPI and is developed on GitHub, at least for the time being.