Support an API for filtering of GenericForeignKeys

[Michał Pasternak]

Hi,

just to let you know, my project that allows filtering of GenericForeignKeys called "djorm-ext-filtered-contenttypes" supports Django versions 1.8-1.11 on Python 2.7, 3.5 and 3.6.

class Foo(models.Model):
   a = GenericForeignKey()

Foo.objects.filter(a__in=[ThisModel, OtherModel, AnotherModel])

My package relies on PostgreSQL and allows to efficiently filter GenericForeignKeys using server-side SQL which looks like:

SELECT ... FROM ... WHERE (t0.content_type_id, t0.object_id) IN (....)

If you add a compound index on t0(content_type_id, object_id)... speed and efficiency.

Check it out: ​https://github.com/mpasternak/djorm-ext-filtered-contenttypes . If there is any interest from core developers, I'm willing to submit a high-quality patch to the main branch, probably living somewhere below contrib.postgresql

[Tim Graham]

Duplicate of #23046. Hi again, three years later. ;-)

Perhaps you can raise the idea on the DevelopersMailingList to get some other feedback. I think many developers avoid GenericForeignKey in the first place so I'm not if enhancing the functionality is a big priority. I noticed several "this is a hack" comments in your project. I would say you should either try to clean those up before moving forward, or explain how inclusion in Django will allow removing the hacks.

[Michał Pasternak]

Hey, yes, I'm back.

I second your opinion. Me myself, I haven't really decided between "I wish I have never used GenericForeignKeys" and "this is cool functionality and PostgreSQL makes it even better". But... if your opinion on this topic reflects the general opinion of the whole Django core team - IDK, maybe it would be better to move GenericForeignKeys to external module and rip them out of Django... or to add some more stuff, likewise as PostgreSQL contrib. Having them in makes the ORM less database-y and more NoSQL...

... but if you look at how are things implemented, they're a terrible hack. Like a bomb waiting to blow up someday.

Anyways, as for me and my small project, I'm glad to be on your radar, just in case.