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
20342	Replace CBV lookup arguments with single `lookup_field` argument.	Tom Christie	Tom Christie	"As discussed on this thread: https://groups.google.com/forum/?fromgroups=#!topic/django-developers/ht6Xq2ytPe4.

SingleObjectMixin currently exposes these three attributes and one method all dealing with queryset filter arguments...

* pk_url_kwarg = 'pk'
* slug_field = 'slug'
* slug_url_kwarg = 'slug'
* get_slug_field()

I was wondering if it would be worth considering simplifying the API somewhat, by moving those three attributes, and that method, into a PendingDeprecation state, and replacing their usage with a single attribute instead, that is used both as the URL kwarg, and as the queryset filter.

* lookup_field = 'pk'

That'd (eventually) lead to a simpler get_object implementation internally, and (immediately) present a slightly nicer, simpler API.

It'd be marginally different in that slug based lookups would require an explicit `lookup_field = 'slug'` to be added to the view,
and also in that it wouldn't handle the case of `slug_field` being set to a different value from `slug_url_kwarg`.

Personally I don't see the later being an issue as:

1. It's not clear to me why you'd ever *need* to use a URL kwarg that's not the same as the filter arg.
2. If it's really something you need to do, then overriding get_object is still really simple, as well as being nice and explicit...

    get_object(self, queryset):
        if queryset is None:
            queryset = self.get_queryset()
        return get_object_or_404(queryset, ...) # whatever custom lookup behavior you need.

To me, the main trade-off seems to be - Is the resulting API enough of an improvement to be worth the change?

I'm more than happy to take on the work, but I guess this ticket might need to go through the design decision needed stage? "	Cleanup/optimization	closed	Generic views	dev	Normal	wontfix		marc.tamlyn@… tom@…	Accepted	1	0	0	0	0	0