Ordering with django-filter backend

[Hoohaha]

django-filter support ordering as well.
User can reuse ordering from django-filter, rather than rest_framework.filters.OrderingFilter

https://django-filter.readthedocs.io/en/stable/ref/filters.html#orderingfilter
Sample code: declare sort param in FilterSet:

class UserFilter(FilterSet):
    account = CharFilter(field_name='username')
    status = NumberFilter(field_name='status')
   
   order_by_field = 'sort'
   sort = OrderingFilter(
        # tuple-mapping retains order
        fields=(
            ('username', 'account'),
            ('first_name', 'first_name'),
            ('last_name', 'last_name'),
        ),

        # labels do not need to retain order
        field_labels={
            'username': 'User account',
        }
    )

    class Meta:
        model = User
        fields = ['first_name', 'last_name']

[sliverc]

The DjangoFilterBackend needs to be adjusted for this to be supported. What do you see is the advantage over the Django REST framework OrderingFilter?

[Hoohaha]

With django-filter backend, you can easily use alias name to sort.
For example, sort a field from foreign relationship. you can use alias name instead of model__foreign__filed.

        fields=(
            ('username', 'account__username'),
            ('first_name', 'account__firstname'),
            ('last_name', 'account__lastname'),
        ),

[sliverc]

Fair enough. I think to support this, only the DjangoFilterBackend needs to be adjusted. Not sure whether something like this should be directly included in DJA or whether it should simply be documented for the users who need it.

The custom django filter backend class which supports ordering could look like the following. This is not tested though and off the top of my head, but should be a starting point.

from rest_framework_json_api.django_filters.backends import DjangoFilterBackend

class DjangoFilterBackendWithOrdering(DjangoFilterBackend):
    def get_filterset_kwargs(self, request, queryset, view):
        filterset_kwargs = super().get_filterset_kwargs(self, request, queryset, view)
        if 'sort' in request.query_params:
            filterset_kwargs['filter_keys'].append('sort')
    return filterset_kwargs

If you have a use case and could test this, adjust as needed and share it, that would be very helpful.