Best way to support multi-login on AppEngine

Question

I'm refactoring for a client an app that should support OpenID, Facebook Connect and custom authentication (email+password). Suppose that i have:

class MyUser(db.Model):
    pass
class Item(db.Model):
    owner = db.ReferenceProperty(MyUser)

I was thinking to implement different authentication systems this way:

class OpenIDLogin(db.Model): # key_name is User.federated_identity()? User.user_id()?
    user = db.ReferenceProperty(MyUser)

class FacebookLogin(db.Model): # key_name is Facebook uid
    user = db.ReferenceProperty(MyUser)

class CustomLogin(db.Model): # key_name is the user email
    user = db.ReferenceProperty(MyUser)
    password = db.StringProperty()

Is there a better solution? There is already an answer here but i can't understand if that's the right solution for me. I've already developed an app using the Users API and another one using Facebook Connect in the past, so i know how to deal with the both, the problem is to wire them together. Switching to another framework isn't an option unfortunately.

Answer 1

I would take a close look at tipfy and its Authentication extension.^*

They have implemented a Universal User model that can be used with App Engine's default users API, own auth or third party authentication methods (OpenId, OAuth etc).

Here is the documentation, look for MultiAuthMixin section.

^{*good programmers write good code; great programmers steal great code}