Feature request: automatic filter negation/exclusion

[aidanlister]

This package supersedes django-rest-framework-filters, but django-rest-framework-filters had a great feature that allows you to do foo!=bar automatically (changes from a filter to an exclude).

https://github.com/philipn/django-rest-framework-filters#automatic-filter-negationexclusion
https://github.com/philipn/django-rest-framework-filters/pull/43/files

This is a nice saving, all of our filtersets look like this:

    text_contains = SearchFilter(fields=['property__name', 'property__client_ref', 'compliancetype__name'], comparison='contains')
    text_excludes = SearchFilter(fields=['property__name', 'property__client_ref', 'compliancetype__name'], comparison='excludes')
    ref_contains = SearchFilter(fields=['property__client_ref'], comparison='contains')
    ref_excludes = SearchFilter(fields=['property__client_ref'], comparison='excludes')
    property_contains = SearchFilter(fields=['property__name'], comparison='contains')
    property_excludes = SearchFilter(fields=['property__name'], comparison='excludes')
    category_contains = SearchFilter(fields=['compliancetype__name'], comparison='contains')
    category_excludes = SearchFilter(fields=['compliancetype__name'], comparison='excludes')

Would you accept a PR that included this functionality?

[zkne]

This feature is much needed!

[carltongibson]

I have no real desire to expand the API of django-filter. (I'm not in favour of automatically extending the filters available: these drive your database, you want to control them.)

However, as I understand it, django-rest-framework-filters just builds on django-filter, so if you like its features, why not just use it?

@rpkilby What is the state of play here? (Thanks!)

[carltongibson]

Also, looking at the diff from the linked PR there, isn't a FilterSet subclass (or decorating class, in the GOF sense) available without too much effort?

[rpkilby]

What is the state of play here?

It's a little complicated. Automatic negation works for most cases, however it runs into issues with multi-valued relationships (see: philipn/django-rest-framework-filters#217). But in general, django-filter doesn't really handling to-many relationships well (#745, #1077), so maybe it should be considered out-of-scope, punting to drf-filters?

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I have no real desire to expand the API of django-filter.

I would agree against expanding the API of the base FilterSet. Automatic negation is a somewhat "magical" feature, and if django-filter were to support it, it should exist as a mixin.

[carltongibson]

Okay, thanks @rpkilby. I’m going to close. Don’t mind seeing examples from users but not ready to include, even as a mixin, at this point.