Query Methods

[Zachary Voase]

The rationale and idea are expounded in more detail in this django-developers thread: ​http://groups.google.com/group/django-developers/browse_thread/thread/ad1af7d783317302

The idea is a simple decorator, similar to Python's @classmethod, which applies to a method on a manager and marks it as a query method—that is, a method which should be present not only on the manager, but on all querysets which come from that manager.

[anonymous]

django-model-utils has a solution to this that was originally from ​http://paulm.us/post/3717466639/passthroughmanager-for-django

[Zachary Voase]

If you take a look at the django-developers thread you'll see I did a similar thing in django-qmixin. The point is, we don't want custom QuerySet subclasses, we want a decorator for methods on the Manager, which Manager.__metaclass__ then uses to dynamically construct a QuerySet subclass.

[Donald Stufft]

django-model-utils used to dynamically generate Querysets to achieve this, which broke pickling them. I don't however know how it was dynamically generated.

In general I think the idea here is to prevent you from having to define the same method twice which that solution has, you just specify it on the QuerySet, then add it to the PassThroughManager. Same Outcome without the metaclass magic which personally find hard to understand with something that gives the same end result.

[Łukasz Rekucki]

This is something definitely worth pursuing, now we just need a good API we can all agree. If anyone wants to work on this, please check the thread for different implementation attempts.

[Fabio Caritas Barrionuevo da Luz]

What is the status of this issue? It is still valid?

[Tomek Paczkowski]

I'd say this has been addressed by as_manager method of QuerySet, here:
​https://docs.djangoproject.com/en/1.7/topics/db/managers/#creating-manager-with-queryset-methods

I'm closing this ticket as fixed. If anyone disagrees, it can always be reopened again.