A rule engine for Django apps.
Project description
A tool to manage logical rules throughout your application. Logical rules are more powerful than permission or rule tables because they are written in python. Register a rule once and work with it throughout your app, from templates to generic view mixins. Instead of cluttering your models with rule-style and permission-style methods define those rules in rules.py and then get easy access to them in your views and templates.
Installation
Use pip to install from PyPI:
pip install django-logical-rules
Add logical_rules to your settings.py file:
INSTALLED_APPS = ( ... 'logical_rules', ... )
Additional Requirements
If you want to use the messaging features install Django messages framework.
Configuration
Rules are defined in rules.py files within your apps. Here’s an example of a rule:
import logical_rules def user_can_edit_mymodel(mymodel, user): """ Confirms a user can edit a specific model ...owners only! """ return mymodel.owner == user logical_rules.site.register("user_can_edit_mymodel", user_can_edit_mymodel)
To include your models in the registry you will need to do run the autodiscover, a bit like django.contrib.admin (I generally put this in urls.py):
import logical_rules logical_rules.autodiscover()
Usage
Template Tag
Once you have created a rule, it’s easy to use anywhere in your templates:
{% load logical_rules_tags %} {% testrule user_can_edit_mymodel object request.user %} <p>You are the owner!</p> {% endtestrule %}
Note: Don’t use quotes around the rule name in the template.
RulesMixin
If you are extending Django’s class-based generic views, you might find this mixin useful. It allows you to define rules that should be applied before rendering a view. Here’s an example usage:
class MyView(RulesMixin, DetailView): def update_logical_rules(self): super(MyView, self).update_logical_rules() self.add_logical_rule({ 'name': 'user_can_edit_mymodel', 'param_callbacks': [('get_request_user', 'get_object')], })
param_callbacks are our technique for getting the parameters for your rule. These are assumed to be methods on your class. get_request_user() is defined in RuleMixin since it’s so common. get_object() is a method on the DetailView class.
Rule dictionaries can have other properties, like redirect_url and response_callback. If redirect_url is defined, then the view will return an HttpResponseRedirect to that URL. If response_callback is defined, then the view will return the result of that method.
Messaging integration is possible with message and message_level options.
Finally, we’ve added two commonly used rules. As an optional substitute for login_required, we have user_is_authenticated and to test a generic expression, we have evaluate_expression.
Direct Calling
import logical_rules if logical_rules.site.test_rule(rule['name'], arg1, arg2): print "passed" else: print "failed"
Contributing
Think this needs something else? To contribute to django-logical-rules create a fork on Bitbucket. Clone your fork, make some changes, and submit a pull request.
Bugs are great contributions too! Feel free to add an issue on Bitbucket:
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