In order to use build a facebook canvas application, you should add this to your MIDDLEWARE_CLASSES setting:
'django_facebook.middleware.FacebookCanvasMiddleWare'- This middleware will check for the signed_request parameter in the url and take the appropriate action:
- redirect to app authorization dialog if user has not authorized the app, some permission is missing or any other error.
- login the current facebook user in django's system and store the access token.