id	summary	reporter	owner	description	type	status	component	version	severity	resolution	keywords	cc	stage	has_patch	needs_docs	needs_tests	needs_better_patch	easy	ui_ux
15494	Using only('pk') in related set raises FieldDoesNotExist	anonymous	Sam Thompson	"This is my first ticket, apologies if this is known or I've missed something in my report.

With model A and model B, where model B has a fk to A:

>>> A().b_set.all().only('pk')

Raises ""FieldDoesNotExist: B has no field named 'pk'""

In my example I'm instantiating a new object for brevity.  The behaviour is the same with a saved object.

I've attached a simple patch, however I couldn't get the testrunner working, so I couldn't write a full patch.  Also, I expect this isn't the best method, but I don't know enough about the ORM to know of a better fix."	Bug	closed	Database layer (models, ORM)	1.2	Normal	fixed			Accepted	1	0	1	1	0	0