current_user proxy for flask example

gistfile1.py

from flask import session, g

current_user = LocalProxy(get_user)  # Global access to the current user

def get_user():
    """
    A proxy for the User model

    Is used as a `LocalProxy` so is context local.
    Uses the `g` object to cache the `User` instance which prevents
    multiple `User` lookups as well as being thread safe.
    """
    # Prevents circular import
    from frontend.user.models import User, AnonymousUser

    # Ensure has session
    if 'user_id' not in session:
        if hasattr(g, '_cached_user'):
            del(g._cached_user)
        return AnonymousUser()

    # If not cached - look it up and cache it
    if not hasattr(g, '_cached_user'):
        try:
            g._cached_user = User.objects.get(id=session['user_id'])
        except:  # Update to capture the correct error eg: except DoesNotExist
            session.pop('user_id')
            return AnonymousUser()
    return g._cached_user