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Djinn role based permission module
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djinn_auth
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README.md

djinn_auth

Role based auth module for Djinn. The package is also usable as standalone module, since it has no relation to other djinn packages.

This module builds upon the django.contrib.auth module, and extends it with role based authorisation, both global roles and local roles (or: roles on a specific model instance). Roles can be assigned to a user and a group.

For (un)assignments you can use the API specified in djinn_auth.utils. This provides functions to assign roles to users/groups globally and locally, and to check on global and local roles. Specific checks enable you to check whether a user has a role, either directly or through one of it's groups.

Note that while this module is agnostic of the specific User model (since this is a swappable model), it will assume at least the existence of the user_permissions relation.

Global permissions

Global permissions provide a means of granting permissions to a user or group globally. This means that a check on a local permission on a given model instance, will also return the global permissions.

You can give a user a permission by:

  1. give the user a permission through the User.user_permissions attribute
  2. give the user a role that has this permission
  3. add the user to a group that has a role that has this permission
  4. add the user to a group that has the permission

Local permissions

You can enable permissions for a given user or group on a specific model instance by:

  1. giving the user a local role on the object with that permission
  2. giving a group the user is part of a local role with that permission
  3. giving the permission to the user on the object
  4. giving the permission to a group the user is part of on the object

To prevent acquisition of the global permissions on an instance, implement the acquire_global_roles property and return False. This enables the scenario where users have a global 'allow', but some local 'forbiddens'. Please note that this only disallows global roles, not direct permissions on the user or it's groups itself.

If you need to add some sort of hierarchy, you may do so using the acquire_from attribute on your instance, that must return a list of instances it wishes to obtain roles/permissions from.

Installation

Install the usual way using pip or easy_install. Add djinn_auth to your INSTALLED_APPS. Add the djinn_auth backend to the AUTHENTICATION_BACKENDS setting:

AUTHENTICATION_BACKENDS = (
  'django.contrib.auth.backends.ModelBackend',
  'djinn_auth.authbackend.AuthBackend'
  )

Usage

Basic use of the djinn_auth module is not different from using the builtin Django authorisation. You can use the same decorators or calls, since djinn_auth adds it's own backend to the autorisation chain. Following, are some simpe cases. Check the utils.py file for the full API. Yes, you will need to read Python code..!

Create a role and add permissions:

from djinn_auth.models import Role
from django.contrib.auth.models import Permission

owner_role = Role.objects.create(name="owner")

do_something = Permission.objects.get(codename="myapp.do_something")

owner_role.add_permission(do_something)

To assign a global role for a user or group (assuming you have a user bobdobalina):

>> from djinn_auth.utils import assign_global_role, has_global_role
>> assign_global_role(bobdobalina, owner_role)
>> has_global_role(bobdobalina, owner_role)
True
>>

This should give us the permission granted to the role (please note that the backend is normally called by the Django auth machinery using the User.has_perm call:

>> from djinn_auth.authbackend import AuthBackend
>> backend = AuthBackend()
>> backend.has_perm(bobdobalina, "myapp.do_something")
True

Revoke it:

>> from djinn_auth.utils import unassign_global_role
>> unassign_global_role(bobdobalina, owner_role)
>> has_global_role(bobdobalina, owner_role)
False
>> backend.has_perm(bobdobalina, "myapp.do_something")
False

Assign a local role:

>> from djinn_auth.utils import assign_local_role, has_local_role
>> instance = MyContentType.objects.get(pk=666)
>> assign_local_role(bobdobalina, instance, owner_role)
>> has_local_role(bobdobaline, instance, owner_role)
True
>> backend.has_perm(bobdobalina, "myapp.do_something")
False
>> backend.has_perm(bobdobalina, "myapp.do_something", obj=instance)
True

Views

To protect class based views, djinn_auth provides a mixin class that adds a permission check: djinn_auth.views.base.PermissionProtectedMixin.

Use like so:

from django.views.generic.base import View
from djinn_auth.views.base import PermissionProtectedMixin

class MyView(PermissionProtectedMixin, View):

    permission = "myapp.view"

or even:

class MyView(PermissionProtectedMixin, View):

    permission = {'GET': 'myapp.view', 'POST': 'myapp.edit'}
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