http://chriskief.com/2012/12/22/django-register-with-oauth-facebook/

facebook.py

import urllib
from django.conf import settings
from django.core.urlresolvers import reverse
from django.core.context_processors import csrf


def get_authorization_url(request):
        # URL to where Facebook will redirect to
        redirect_url = urllib.quote_plus(settings.SITE_URL + reverse('register_facebook'))

        # create a unique state value for CSRF validation
        request.session['facebook_state'] = unicode(csrf(request)['csrf_token'])

        # redirect to facebook for approval
        url = 'https://www.facebook.com/dialog/oauth?' \
              + 'client_id=' + settings.FACEBOOK_APP_ID \
              + '&redirect_uri=' + redirect_url \
              + '&scope=email' \
              + '&state=' + request.session['facebook_state']

        return url