rest-framework-roles 0.2.3

Role-based permissions for Django REST Framework and vanilla Django.

REST Framework Roles

Role-based permissions for Django and Django REST Framework.

• Data-driven declarative permissions decoupled from views and models.
• Roles are implementation agnostic. You can utilize the database or a dict or anything in between.
• Role checking can easily be optimized by simply annotating with a cost.
• Permissions applied on a view-basis ensuring redirections don't introduce security holes.
• Support for Django and REST Framework - working with class-based and function-based views.
• Easy gradual integration with existing Django REST Framework projects.

Install

Install

pip install rest-framework-roles

settings.py

INSTALLED_APPS = {
    ..
    'rest_framework',
    'rest_framework_roles',  # Must be after rest_framework
}

REST_FRAMEWORK_ROLES = {
  'roles': 'myproject.roles.ROLES',
}

REST_FRAMEWORK = {
  ..
  'permission_classes': [],  # This ensures that by default noone is allowed access
  ..
}

roles.py

from rest_framework_roles.roles import is_user, is_anon, is_admin


ROLES = {
    'admin': is_admin,
    'user': is_user,
    'anon': is_anon,
}

You can create your own role checkers for custom roles. Each checker is a simple function that takes request and view as arguments.

REST Framework example

Permissions can be set either with the decorators @allowed, @disallowed or view_permissions. Permission is granted for any matching role. In case of no matching role, REST Framework's permission_classes is used as fallback.

Views not explicitly set any permissions will simply fall to their default behaviour. This ensures smooth integration with existing projects.

views.py

from rest_framework.viewsets import ModelViewSet
from rest_framework_roles.permissions import is_self


class UserViewSet(ModelViewSet):
    serializer_class = UserSerializer
    queryset = User.objects.all()

    view_permissions = {
        'retrieve': {'user': is_self, 'admin': True},
        'create': {'anon': True},
        'list': {'admin': True},
    }

    @allowed('admin', 'user')
    @action(detail=False, methods=['get'])
    def me(self, request):
        self.kwargs['pk'] = request.user.pk
        return self.retrieve(request)

Note the permission for 'retrieve'. We need to include an explicit permission for 'admin' or else the admin user will only be able to retrieve himself (matching the user role).

Advanced example

Sometimes you want to deal with more complex scenarios. Still this is way simpler than using permission_classes or similar as demonstrated below.

from rest_framework_roles.permissions import is_self
from rest_framework_roles import roles


class UserViewSet(ModelViewSet):
    serializer_class = UserSerializer
    queryset = User.objects.all()
    view_permissions = {
        'retrieve': {'user': is_self},
        'update': {'user': is_self, 'admin': True},
        'create': {'anon': True},
        'list': {'admin': True},
        'me': {'user': True},
    }

    def update(self, request, **kwargs):
        # Allow only admin to change user's username
        if 'username' in request.data and not roles.is_admin(request, self):
            raise PermissionDenied('Only admin can change username')
        return super().update(request, **kwargs)

    @action(detail=False, methods=['get', 'patch'])
    def me(self, request):
        self.kwargs['pk'] = request.user.pk
        if request.method == 'GET':
            return self.retrieve(request)
        elif request.method == 'PATCH':
            return self.partial_update(request)

In this example:

1. User can retrieve himself.
2. User or admin can update himself, but 'username' is only allowed to be updated by admin.
3. Only anonymous can create a user account.
4. Action 'me' can be used for both retrieval and partial update.

Advanced roles

By default you get some role-checking functions for common roles like 'admin', 'user' and 'anon'. Many times though, you have many more roles and certain roles can be expensive to calculate.

For this reason role-checking functions can be marked by a cost. The lower cost roles are checked first and then the expensive ones until a role matches that does not get granted permission.

from rest_framework_roles.decorators import role_checker


@role_checker(cost=0)
def is_freebie_user(request, view):
    return request.user.is_authenticated and request.user.plan == 'freebie'


@role_checker(cost=0)
def is_payed_user(request, view):
    return request.user.is_authenticated and not request.user.plan


@role_checker(cost=50)
def is_creator(request, view):
    obj = view.get_object()
    if hasattr(obj, 'creator'):
        return request.user == obj.creator
    return False

This is a bit similar to Django REST's check_permissions and check_object_permissions but much more powerful since you can refine the order of the role checking to the level you want.