django-guardian

django-guardian is implementation of per object permissions¹ as authorization backend which is supported since Django 1.2. It won't work with older Django releases.

Documentation

Online documentation is available at http://django-guardian.rtfd.org/.

Installation

To install django-guardian simply run:

pip install django-guardian

Configuration

We need to hook django-guardian into our project.

1. Put guardian into your INSTALLED_APPS at settings module:

   INSTALLED_APPS = (
      ...
      'guardian',
   )

2. Add extra authorization backend:

   AUTHENTICATION_BACKENDS = (
       'django.contrib.auth.backends.ModelBackend', # default
       'guardian.backends.ObjectPermissionBackend',
   )

3. Configure anonymous user ID :

   ANONYMOUS_USER_ID = -1

Usage

After installation and project hooks we can finally use object permissions with Django.

Lets start really quickly:

>>> jack = User.objects.create_user('jack', 'jack@example.com', 'topsecretagentjack')
>>> admins = Group.objects.create(name='admins')
>>> jack.has_perm('change_group', admins)
False
>>> UserObjectPermission.objects.assign_perm('change_group', user=jack, obj=admins)
<UserObjectPermission: admins | jack | change_group>
>>> jack.has_perm('change_group', admins)
True

Of course our agent jack here would not be able to change_group globally:

>>> jack.has_perm('change_group')
False

Admin integration

Replace admin.ModelAdmin with GuardedModelAdmin for those models which should have object permissions support within admin panel.

For example:

from django.contrib import admin
from myapp.models import Author
from guardian.admin import GuardedModelAdmin

# Old way:
#class AuthorAdmin(admin.ModelAdmin):
#    pass

# With object permissions support
class AuthorAdmin(GuardedModelAdmin):
    pass

admin.site.register(Author, AuthorAdmin)

---

1. Great paper about this feature is available at djangoadvent articles.↩