django: filter queryset when 2 fields have same value

Question

I have a model which has 2 fields like,

pickup_station_id = models.IntegerField(null=True)
drop_station_id = models.IntegerField(null=True)

I want a filter in admin which can filter the queryset based on,

• pickup and drop ids are different
• pickup and drop ids are same

How can I get a queryset based on these conditions?

I mean, something like this,

Mymodel.objects.filter(pickup_station_id==drop_station_id)

Mymodel.objects.filter(pickup_station_id!=drop_station_id)

Answer 1

You can refer to a f ield with an F -expression [Django-doc] . So we can write it like:

from django.db.models import 

Mymodel.objects.filter(pickup_station_id=)

We can negate a q uery by using a Q -object [Django-doc] :

from django.db.models import F, 

Mymodel.objects.filter(pickup_station_id=F('drop_station_id'))

Here the tilde ( ~ ) means we negate the condition that the Q object represents.