Question

I’m after a django query that will allow me to list all items which do and do-not have any certain related objects.

For example if I have the models:

def Customer(Model):
    name = CharField(...)
    ...

def Order(Model):
    customer = ForeignKey(Customer)

Now, how do I say “Give me all customers with orders, and conversely, give me all customers without orders”?

What I have so far (which doesn’t work) is this:

withords = model.objects.all().annotate(orders=Count('order')).filter(orders__gt=0)

without = model.objects.all().annotate(orders=Count('order')).filter(orders__lt=1)

Any ideas?

Answer 1

How about:

All customers with orders:

Customer.objects.filter(order__isnull=False).distinct()

All customers without orders:

Customer.objects.filter(order__isnull=True)