How to order query results based on amount of relations?

[notramo]

There is an User model, and each User can have multiple Post records. How to query all users ordered by the amount of posts they have?

[ellmetha]

Currently, this functionality isn't available, regrettably. It would require query set annotations. For instance, the ability to annotate a query set with a count aggregate and then utilize it (as part of the query set) to order records. This is something we should implement at one point.