django-permission

Author

Alisue <[email protected]>

Supported python versions

Python 2.6, 2.7, 3.2, 3.3

Supported django versions

Django 1.2 - 1.6

An enhanced permission library which enable logic based permission system to handle complex permissions in Django.

It is developed based on authentication backend system introduced from django 1.2. This library support Django 1.2 and later.

Documentation

http://django-permission.readthedocs.org/en/latest/

Installation

Use pip like:

$ pip install "django-permissions>=0.5.0"

Usage

Configuration

1. Put permission into your INSTALLED_APPS at settings module

   INSTALLED_APPS = (
       # ...
       'permission',
   )

2. Add extra authorization backend

   AUTHENTICATION_BACKENDS = (
       'django.contrib.auth.backends.ModelBackend', # default
       'permission.backends.PermissionBackend',
   )

3. Follow the instruction below to apply logical permissions to django models

Apply permission logic

Assume you have an article model which has author attribute to store who creat the article and you want to give the author full controll permissions (e.g. add, change, delete permissions).

What you need to do is just applying permission.logics.AuthorPermissionLogic to the Article model like

from django.db import models
from django.contrib.auth.models import User


class Article(models.Model):
    title = models.CharField('title', max_length=120)
    body = models.TextField('body')
    author = models.ForeignKey(User)

    # this is just required for easy explanation
    class Meta:
        app_label='permission'

# apply AuthorPermissionLogic
from permission import add_permission_logic
from permission.logics import AuthorPermissionLogic
add_permission_logic(Article, AuthorPermissionLogic())

That's it. Now the following codes will work as expected

user1 = User.objects.create_user(
    username='john',
    email='[email protected]',
    password='password',
)
user2 = User.objects.create_user(
    username='alice',
    email='[email protected]',
    password='password',
)

art1 = Article.objects.create(
    title="Article 1",
    body="foobar hogehoge",
    author=user1
)
art2 = Article.objects.create(
    title="Article 2",
    body="foobar hogehoge",
    author=user2
)

# You have to apply 'permission.add_article' to users manually because it
# is not object permission.
from permission.utils.permissions import perm_to_permission
user1.user_permissions.add(perm_to_permission('permission.add_article'))

assert user1.has_perm('permission.add_article') == True
assert user1.has_perm('permission.change_article') == False
assert user1.has_perm('permission.change_article', art1) == True
assert user1.has_perm('permission.change_article', art2) == False

assert user2.has_perm('permission.add_article') == False
assert user2.has_perm('permission.delete_article') == False
assert user2.has_perm('permission.delete_article', art1) == False
assert user2.has_perm('permission.delete_article', art2) == True

#
# You may interested in django signals to apply 'add' permissions to the
# newly created users.
# https://docs.djangoproject.com/en/dev/ref/signals/#django.db.models.signals.post_save
#
from django.db.models.signals.post_save
from django.dispatch import receiver
from permission.utils.permissions import perm_to_permission

@receiver(post_save, sender=User)
def apply_permissions_to_new_user(sender, instance, created, **kwargs):
    if not created:
        return
    #
    # permissions you want to apply to the newly created user
    # YOU SHOULD NOT APPLY PERMISSIONS EXCEPT PERMISSIONS FOR 'ADD'
    # in this way, the applied permissions are not object permission so
    # if you apply 'permission.change_article' then the user can change
    # any article object.
    #
    permissions = [
        'permission.add_article',
    ]
    for permission in permissions:
        # apply permission
        # perm_to_permission is a utility to convert string permission
        # to permission instance.
        instance.user_permissions.add(perm_to_permission(permission))

See http://django-permission.readthedocs.org/en/latest/_modules/permission/logics/author.html#AuthorPermissionLogic to learn how this logic works.

Now, assume you add collaborators attribute to store collaborators of the article and you want to give them a change permission.

What you need to do is quite simple. Apply permission.logics.CollaboratorsPermissionLogic to the Article model like

from django.db import models
from django.contrib.auth.models import User


class Article(models.Model):
    title = models.CharField('title', max_length=120)
    body = models.TextField('body')
    author = models.ForeignKey(User)
    collaborators = models.ManyToManyField(User)

    # this is just required for easy explanation
    class Meta:
        app_label='permission'

# apply AuthorPermissionLogic and CollaboratorsPermissionLogic
from permission import add_permission_logic
from permission.logics import AuthorPermissionLogic
from permission.logics import CollaboratorsPermissionLogic
add_permission_logic(Article, AuthorPermissionLogic())
add_permission_logic(Article, CollaboratorsPermissionLogic(
    field_name='collaborators',
    any_permission=False,
    change_permission=True,
    delete_permission=False,
))

That's it. Now the following codes will work as expected

user1 = User.objects.create_user(
    username='john',
    email='[email protected]',
    password='password',
)
user2 = User.objects.create_user(
    username='alice',
    email='[email protected]',
    password='password',
)

art1 = Article.objects.create(
    title="Article 1",
    body="foobar hogehoge",
    author=user1
)
art1.collaborators.add(user2)

assert user1.has_perm('permission.change_article') == False
assert user1.has_perm('permission.change_article', art1) == True
assert user1.has_perm('permission.delete_article', art1) == True

assert user2.has_perm('permission.change_article') == False
assert user2.has_perm('permission.change_article', art1) == True
assert user2.has_perm('permission.delete_article', art1) == False

See http://django-permission.readthedocs.org/en/latest/_modules/permission/logics/collaborators.html#CollaboratorsPermissionLogic to learn how this logic works.

Customize permission logic

Your own permission logic class must be a subclass of permission.logics.PermissionLogic and must override has_perm(user_obj, perm, obj=None) method which return boolean value.

Class, method, or function decorator

Like Django's permission_required but it can be used for object permissions and as a class, method, or function decorator. Also, you don't need to specify a object to this decorator for object permission. This decorator automatically determined the object from request (so you cannnot use this decorator for non view class/method/function but you anyway use user.has_perm in that case).

>>> from permission.decorators import permission_required
>>> # As class decorator
>>> @permission_required('auth.change_user')
>>> class UpdateAuthUserView(UpdateView):
...     pass
>>> # As method decorator
>>> class UpdateAuthUserView(UpdateView):
...     @permission_required('auth.change_user')
...     def dispatch(self, request, *args, **kwargs):
...         pass
>>> # As function decorator
>>> @permission_required('auth.change_user')
>>> def update_auth_user(request, *args, **kwargs):
...     pass

Overwrite builtin if in template

django-permission overwrite builtin if tag to add two operator to handle permission in template. You can specify permission with has keyword and object with of keyword like the below.

{% if user has 'blogs.add_article' %}
    <p>This user have 'blogs.add_article' permission</p>
{% elif user has 'blog.change_article' of object %}
    <p>This user have 'blogs.change_article' permission of {{object}}</p>
{% endif %}

{# If you set 'PERMISSION_REPLACE_BUILTIN_IF = False' in settings #}
{% permission user has 'blogs.add_article' %}
    <p>This user have 'blogs.add_article' permission</p>
{% elpermission user has 'blog.change_article' of object %}
    <p>This user have 'blogs.change_article' permission of {{object}}</p>
{% endpermission %}