自定义user_logged_in信号之前django更新last_login

Question

I'd like to show a notification to user with some stats (eg how many items have been sold since last time he logged in)

@receiver(user_logged_in)
def notify_user_on_login(sender, request, user, **kwargs):    
    items = Item.objects.filter(status=Item.HISTORY_STATUS, seller=user, when_trading__gte=user.last_login)

However, in this signal last_login has already been updated. According to the source at django.contib.auth django also connects signal with function that updates last_login :

user_logged_in.connect(update_last_login)

Is it possible to call my function BEFORE updating? Or get same result without adding custom field or doing some strange magic?

Answer 1

The last_login is also updated with a handler to that signal, which is surely registered and executed before yours. You might be able to solve your issue by moving your app over django.contrib.auth in INSTALLED_APPS .

Signal handlers depending on order doesn't seem like a good idea though. So I would probably replace Django's handler with your own:

from django.contrib.auth.models import update_last_login

def notify_user_on_login(user):    
    items = Item.objects.filter(status=Item.HISTORY_STATUS, seller=user, when_trading__gte=user.last_login)


@receiver(user_logged_in)
def after_user_logged_in(sender, user, **kwargs):
    notify_user_on_login(user)
    update_last_login(sender, user, **kwargs)

user_logged_in.disconnect(update_last_login)