auth signal receiver update_last_login not compatible with custom user models that have no last_login field

[Harry Percival]

In my experiments with building a minimal custom user model, I've managed to build one that has just one field, email. Which I think is brilliant of course. One feature in the auth module is stopping it from working though, the update_last_login signal receiver from contrib.auth.models, which is wired up in auth.signals.user_logged_in.

My workaround is to do a

from django.contrib import auth
auth.signals.user_logged_in.disconnect(auth.models.update_last_login)

But we could make the signal handler more resilient. Something like this?

def update_last_login(sender, user, **kwargs):
    if not hasattr(user, 'last_login'):
        return

PR to follow...

[Harry Percival]

cf ​https://github.com/django/django/pull/6855

[Tim Graham]

An alternative implementation I thought of would be to introspect the user model and see if it has a last_login field and avoid connecting the signal if not. I'm not sure it's feasible with user_logged_in.connect(update_last_login) at the module level since get_user_model() can't be called there, but maybe if the signal connecting happened in AuthConfig.ready() that could work?

[Claude Paroz]

+1 to connect the signal in ready()

[Florian Apolloner]

Signal connection in ready() should not be done lightly, this method should be idempotent -- either just import a module from there or make sure to set dispatch_uid

[Linus Lewandowski]

​PR.

[Tim Graham <timograham@…>]

In eedc88bd:

Fixed #26823 -- Prevented update_last_login signal receiver from crashing if User model doesn't have last_login field.