How to change the Django admin filter to use a dropdown instead of list?

Thanks @beholderrk, @gediminas and @jk-laiho! I packaged this into a reusable app.

Install:

pip install django-admin-list-filter-dropdown

Enable in settings.py:

INSTALLED_APPS = (
    ...
    'django_admin_listfilter_dropdown',
    ...
)

Use in admin.py:

from django_admin_listfilter_dropdown.filters import (
    DropdownFilter, ChoiceDropdownFilter, RelatedDropdownFilter
)

class EntityAdmin(admin.ModelAdmin):
    ...
    list_filter = (
        # for ordinary fields
        ('a_charfield', DropdownFilter),
        # for choice fields
        ('a_choicefield', ChoiceDropdownFilter),
        # for related fields
        ('a_foreignkey_field', RelatedDropdownFilter),
    )

Here’s what it looks like: