Example Authentication Wrapper

Handling authentication with a wrapper just feels clean.

from functools import wraps
from pycnic.core import WSGI, Handler
from pycnic.errors import HTTP_401

def get_user_role(request):
    # Normally you'd do something like
    # check for request.cookies["session_id"]
    # existing in memcache or a database, but
    # for now... everyone's an admin!
    return "admin"

def requires_roles(*roles):
    def wrapper(f):
        def wrapped(*args, **kwargs):
            if get_user_role(args[0].request) not in roles:
                raise HTTP_401("I can't let you do that")
            return f(*args, **kwargs)
        return wrapped
    return wrapper

class UserHandler(Handler):

    @requires_roles("admin", "user")
    def get(self):
        return { "message":"Welcome, admin!" }

    def post(self):
        self.response.status_code = 201
        return { "message":"New user added!" }

class app(WSGI):
    routes = [ ('/user', UserHandler()) ]

As you can see from above, either a user or admin can perform a GET request against the UserHandler, but only an admin can POST to it.

In that example, get_user_role() is a dummy function that blindly returns "admin" for each user.