Getting Started with the Python Fat Cookie Library

First follow the Installing Python Fat Cookie Library first then proceed.

Basic Pycookie Usage

Some basic example usage:

>>> import pycookie
>>> fc = pycookie.FatCookie('CUT AND PASTE FROM `FC` COOKIE')
>>> fc.eid
'Your EID'
>>> fc.uin
'Your UIN'

Integrating Pycookie Into Django

These are simple examples of how to ‘authenticate’ users in django with the pycookie module.

Authenticate a User in a Request

In your views.py file you can require that someone is logged in to see one paticular view. Or just use the cookie info to identify the logged in user. To lock down a single view you could write something like this:

from django.http import HttpResponseRedirect
from django.shortcuts import render_to_response
from django.template.context import RequestContext

import pycookie

def secure_view(request):
    try:
        fat_cookie = request.cookies.get('FC', None)
        user = pycookie.FatCookie(fat_cookie)
    except pycookie.FatCookieException:
        return HttpResponseRedirect('https://utdirect.utexas.edu')
    # write your view code here
    # check for a paticular user like so:
    admin = False
    if user.eid == 'admin_eid':
        admin = True
    return render_to_response('template.html', RequestContext({
                              'user': user,
                              'admin': admin,
                              }))

Now you say do I have to do this in every view? No. You can write a decorator which will wrap the check code for a valid Fat Cookie around any view you choose. The decorator function would look like this:

from django.http import HttpResponseRedirect
from django.shortcuts import render_to_response
from django.template.context import RequestContext

import pycookie

def require_uteid(func):
    def _dec(request, *args, **kwargs):
        try:
            fat_cookie = request.cookies.get('FC', None)
            user = pycookie.FatCookie(fat_cookie)
            request.ut_user = user
            return func(request, *args, **kwargs)
        except pycookie.FatCookieException:
            return HttpResponseRedirect('https://utdirect.utexas.edu')
return _dec

Now to use the decorator you just do this in Python 2.4 or greater:

@require_uteid
def secure_view(request):
    # check the user
    if request.ut_user.eid == 'admin_eid':
        admin = True
    # rest of your view

In Python 2.3 it would look like this:

def secure_view(request):
    # check the user
    if request.ut_user == 'admin_eid':
        admin = True
    # rest of your view

secure_view = require_uteid(secure_view)

Using Middleware to Require EID on Entire Site

Sometimes you want to have an entire site protected by eid or to automatically create user when a new person logs in. First you will need to write a middleware class to handle logging users in. Middleware is run everytime Django processes a request or response, so you alter the request or response anyway you see fit. This is a perfect way to check if a person is logged in or not.

The following middleware would replace Django’s ‘AuthenticationMiddleware’ place the following in your app directory in a file named middleware.py:

from django.http import HttpResponseRedirect
from django.contrib.auth.models import AnonymousUser

import pycookie

class UTUser(AnonymousUser):
    """AnonymousUser has the properties of a Django User
    we use it to appear like we have a Django User object.
    """
    def __init__(self, fat_cookie):
         self.id = fat_cookie.uin
         self.username = fat_cookie.eid
         name = fat_cookie.name.split(' ')
         self.first_name = name[0]
         self.last_name = name[-1]

    def is_anonymous(self):
        return False

    def is_authenticated(self):
        return True

class LazyUser(object):
    def __get__(self, request, obj_type=None):
        if not hasattr(request, '_cached_user'):
            try:
                fat_cookie = request.cookies.get('FC', None)
                user = pycookie.FatCookie(fat_cookie)
                request._cached_user = UTUser(user)
            except pycookie.FatCookieException:
                return HttpResponseRedirect('https://utdirect.utexas.edu')
        return request._cached_user

class FCAuthenticationMiddleware(object):
    def process_request(self, request):
        assert hasattr(request, 'session'), "Requires 'django.contrib.sessions.middleware.SessionMiddleware'."
        request.__class__.user = LazyUser()
        return None

Now you just need to ‘install’ the middleware edit your settings.py file and modify the MIDDLEWARE_CLASSES like this:

MIDDLEWARE_CLASSES = (
    'django.middleware.common.CommonMiddleware',
    'django.contrib.sessions.middleware.SessionMiddleware',
    'my_app.middleware.FCAuthenticationMiddleware',
)