Use related_objects api for Django 1.9+

[andreif]

Closes #3252.

[lovelydinosaur]

This sort of version-branching code should go into combat.py

We'll want eg a get_all_related_objects(opt) function, and a get_all_related_many_to_many_objects(opt) function.

Looking good tho!

[andreif]

@tomchristie Yeah, I started so, but then decided to move it to the only place where it's used and there are already some compat things in the method. Do you want to move all compat-related things to compat.py or just the latest addition?

[andreif]

It's probably better to use django version check instead of getattr. What do you think, should I change it?

[lovelydinosaur]

Do you want to move all compat-related things to compat.py or just the latest addition?

Just stuff that has a version switch.

It's probably better to use django version check instead of getattr.

Agree. The version check is fine.

[andreif]

@tomchristie With version check I meant the lines which are already there, e.g.

related = getattr(relation, 'related_model', relation.model)

Do you prefer to move them as well e.g. related_model(opts)?

[lovelydinosaur]

If there's a newer 1.9 API that we should be using instead then yes. Otherwise no.

[andreif]

@tomchristie done.

[lovelydinosaur]

Perfect!