class Service(Model):
name = ...
price = ...
class Order(Model):
service = ForeignKey(Service, related_name=u'orders')
user = ForeignKey(User, related_name=u'orders')
done = BooleanField(default=False)
...
orders_by_user_and_service = some_service.orders.filter(user=some_user_instance, done=True)
# or
orders_by_user_and_service = some_user.orders.filter(service=some_service_instance, done=True)
# or
orders_by_user_and_service = Orders.objects.filter(user=some_user_instance, service=some_service_instance, done=True)
# or
orders_by_user_and_service = Orders.objects.filter(user_id=some_user_id, service_id=some_service_id, done=True)
...
