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
19722	GenericRelation in a subclass, filtering by a field of the GFK-declaring model fails	Ramiro Morales	Ramiro Morales	"This was report in a comment by user 'nator' to #11263, is a different issue to the one initially discussed in that ticket. Quoting:

''Say we have a non-abstract superclass and a subclass, and we add a GR relationship to the subclass:''
{{{
class Order(models.Model):
    content_type = models.ForeignKey(ContentType)    
    object_id = models.PositiveIntegerField()
    content_object = generic.GenericForeignKey()
    status = models.CharField(max_length=10, default='ordered')
    
class Media(models.Model):
    order = generic.GenericRelation(Order)

class Photo(Media):
    title = models.CharField()

Photo.objects.filter(order__status='ordered').count()
--> doesn't break, but always returns 0.
}}}

''The basic problem is that when the Order object is created Django inserts it into the DB using the content_type of Photo, but when the select is run Django realizes Order actually lives in Media and tries to use that content_type. So the inserts all ""work"", but the count() never finds them. It's a mismatch between the content_type_id when it runs the insert and select.

After digging through django/config/contenttypes/generic.py a bit I feel like the correct answer is to change the inserts to use the content_type of the class that actually contains the m2m relationship. (Media, in this case).''

There is a proposed fix attached to that ticket."	Bug	closed	contrib.contenttypes	dev	Normal	fixed			Ready for checkin	1	0	0	0	0	0