django-rulez 1.0.2
A lean and mean object-level rules system for the Django framework
License: BSD
Keywords: authorization,backends,django,rules,permissions,rulez

.. |travisci| image:: https://api.travis-ci.org/chrisglass/django-rulez.png
.. _travisci https://travis-ci.org/chrisglass/django-rulez

|travisci|

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django-rulez
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django-rulez is a lean, fast and complete rules-based permissions system for
the django framework.

Most other authentication frameworks focus on using database joins, which gets
pretty slow after a while (since mostly every query generates a lot of joins).
Django-rulez uses a memory-based hashmap instead.

Django-rulez also implements a role concept, allowing for very readable and
maintainable code.

django-rulez was forked from django-rules, since some of the goals django-rules
set themselves didn't match our current project goals. You can refer to their 
github project page for more information about this other cool project: 
https://github.com/maraujop/django-rules
Kudos for the good work guys!

Generally, it is also an instance-level authorization backend, that stores the 
rules themselves as methods on models.

Status
======

Since many people asked - this project is still active and used in production
systems, but its current goals have been reached and not much further
development happens.

Pull requests or discussion is very welcome, especially if you have an
interesting use-case we haven't thought of :)

Our test coverage is 100%, and we would like to keep it this way, so
please make sure you test before you push.

Installation
=============


From source
------------

To install django-rulez from source::

	git clone https://github.com/chrisglass/django-rulez/ django-rulez
	cd django-rulez
	python setup.py install

From Pypi
----------

Simply install django-rulez like you would install any other pypi package::

    pip install django-rulez


Configuration
==============

* Add `rulez` to the list of `INSTALLED_APPS` in your `settings.py`
* Add the django-rulez authorization backend to the list of `AUTHENTICATION_BACKENDS` in `settings.py`::

	AUTHENTICATION_BACKENDS = [
	    'django.contrib.auth.backends.ModelBackend', # Django's default auth backend
	    'rulez.backends.ObjectPermissionBackend',
	]

Example
=========

The following example should get you started::

    # models.py
    from rulez import registry
    
    class myModel(models.Model):
        
        def can_edit(self, user_obj):
            '''
            Not a very useful rule, but it's an example
            '''
            if user_obj.username == 'chris':
                return True
            return False
            
    registry.register('can_edit', myModel)

Django-rulez requires to declare the rule as a method in the same model. This
is very simple in case the rule applies to a model in our own application, but
in some cases, we might need to set object permisions to models from 3rd-party
applications (e.g. to the User model). Let's see an example for this case::

    # models.py
    from django.contrib.auth.models import User
    from rulez import registry
    
    def user_can_edit(self, user_obj):
        '''
        This function will be hooked up to the User model as a method.
        The rule says that a user can only be modified by the same user
        '''
        if self == user_obj:
            return True
        return False
    
    # 'add_to_class' is a standard Django method
    User.add_to_class('can_edit', user_can_edit)
            
    registry.register('can_edit', User)

Another example: using roles
=============================

A little more code is needed to use roles, but it's still pretty concise::

    # models.py
    from rulez.rolez.base import AbstractRole
    from rulez.roles.models import ModelRoleMixin
    from rulez import registry

    class Editor(AbstractRole):
        """ That's a role"""
        @classmethod
        def is_member(cls, user, obj):
            """Remember, class methods take the class instead of self"""
            if user.username == 'chris':
                return True
            return False

    class myModel(models.Model, ModelRoleMixin): # Don't forget the mixin!
        
        def can_edit(self, user_obj):
            '''
            Not a very useful either but it's an example
            '''
            return self.has_role(user_obj, Editor):

        roles = [Editor, ]

    registry.register('can_edit', myModel)

Using your rules
=================

Once you have created a rule or role, you can utilize them directly on 
an instance of your model:::

    model_instance = MyModel.objects.get(pk=1)
    user_chris = User.objects.get(username='chris')

    model_instance.can_edit(user_chris)

Or, with the help of django-rulez's authentication backend, on a user 
object:::

    user_chris.has_perm('can_edit', model_instance)

In addition, the following templatetag usage is supported:::

   {% load rulez_perms %}
   {% rulez_perms can_edit model_instance as VARNAME %}
   {% if VARNAME %}
   You have permissions
   {% else %}
   Sorry, you don't have permission
   {% endif %}