Django: signal when user logs in?

Question

In my Django app, I need to start running a few periodic background jobs when a user logs in and stop running them when the user logs out, so I am looking for an elegant way to

1. get notified of a user login/logout
2. query user login status

From my perspective, the ideal solution would be

1. a signal sent by each django.contrib.auth.views.login and ... views.logout
2. a method django.contrib.auth.models.User.is_logged_in(), analogous to ... User.is_active() or ... User.is_authenticated()

Django 1.1.1 does not have that and I am reluctant to patch the source and add it (not sure how to do that, anyway).

As a temporary solution, I have added an is_logged_in boolean field to the UserProfile model which is cleared by default, is set the first time the user hits the landing page (defined by LOGIN_REDIRECT_URL = '/') and is queried in subsequent requests. I added it to UserProfile, so I don't have to derive from and customize the builtin User model for that purpose only.

I don't like this solution. If the user explicitely clicks the logout button, I can clear the flag, but most of the time, users just leave the page or close the browser; clearing the flag in these cases does not seem straight forward to me. Besides (that's rather data model clarity nitpicking, though), is_logged_in does not belong in the UserProfile, but in the User model.

Can anyone think of alternate approaches ?

Answer 1

You can use a signal like this (I put mine in models.py)

from django.contrib.auth.signals import user_logged_in


def do_stuff(sender, user, request, **kwargs):
    whatever...

user_logged_in.connect(do_stuff)

See django docs: https://docs.djangoproject.com/en/dev/ref/contrib/auth/#module-django.contrib.auth.signals and here http://docs.djangoproject.com/en/dev/topics/signals/