How to filter ForeignKey Django?

Question

Django

In chat, I need to get the number of unread messages for the user and I can't seem to get it done with django orm, here's a sketch:

chat.message_set.exclude(readers__contains=user).count()

But it fails with the corresponding error:
django.core.exceptions.FieldError: Related Field got invalid lookup:
contains

sum([1 for m in self.message_set.all() if user in m.readers.all()])

Can you please tell me how to solve this problem more efficiently?
Update:
I came up with a poor solution for me, but working and generally fast:
In the message model, all readers are stored in the ManyToManyField connection, which causes an error, or you can put all reader logins in one line and apply __contains to it already

Answer 1

duy read the docs https://docs.djangoproject.com/en/4.0/topics/db/qu...