My initial question was here and was related to the postgres backend. http://stackoverflow.com/questions/2408965/postgres-subquery-ordering-by-subquery

Now my problem has moved onwards to the Django ORM layer. I essentially want to order a query by a postgres function ('idx', taken from the above stackoverflow work)

I've gone through trying to use model.objects.extra(order_by ) or simply order_by but I believe both of these need the order_by parameter to be an attribute or a field known to Django.

I'm trying to think how to solve this without having to revert to using an entirely raw SQL query through a model manager.