使用django-filter进行不区分大小写的排序

Question

Is it possible to do case-insensitive ordering by first_name with Django-rest-framework .

Here is the code:

import django_filter

class PersonFilter(django_filters.FilterSet):
    class Meta:
        model = Person
        fields = ('first_name_lower',)
        order_by = ('first_name_lower',)

class PersonViewSet(BaseModelViewSet):
    queryset = Person.objects.all()
    permission_classes = (permissions.IsAuthenticated,)
    filter_backends = (filters.DjangoFilterBackend,)
    filter_class = PersonFilter

Is there an easy way to do case-insensitive ordering with django-filter ?

Here django-filter has docs for case-insensitive search , but nothing for ordering .

In the Django docs, the code is somewhat obtuse for this, which makes me wonder if it exists for django-filter or not. Here's the Django docs code snippet on how to do it with the Django ORM:

>>> from django.db.models.functions import Lower
>>> MyModel.objects.order_by(Lower('myfield'))

Answer 1

You might want to subclass the OrderingFilter and use it as your filter_backend so that you can reuse the code.

from rest_framework.filters import OrderingFilter
from django.db.models.functions import Lower

class CaseInsensitiveOrderingFilter(OrderingFilter):
    def filter_queryset(self, request, queryset, view):
        ordering = self.get_ordering(request, queryset, view)

        if ordering is not None:
            if ordering.startswith('-'):
                queryset = queryset.order_by(Lower(ordering[1:])).reverse()
            else:
                queryset = queryset.order_by(Lower(ordering))
        return queryset


class PersonViewSet(ModelViewSet):
    queryset = Person.objects.all()
    serializer_class = MySerializer
    permission_classes = (permissions.IsAuthenticated,)
    filter_backends = (CaseInsensitiveOrderingFilter,)

Answer 2

The case-insensitive search can be done by overriding the get_queryset method on the ModelViewSet class.

It works for descending and ascending case-insensitive ordering.

# Example URL's
'/api/people/?ordering=-first_name'
'/api/people/?ordering=first_name'

Here's the code:

class PersonViewSet(ModelViewSet):
    queryset = Person.objects.all()
    serializer_class = MySerializer
    permission_classes = (permissions.IsAuthenticated,)

    def get_queryset(self):
        queryset = self.queryset
        ordering = self.request.query_params.get('ordering', None)
        if ordering is not None:
            from django.db.models.functions import Lower
            if ordering.startswith('-'):
                queryset = queryset.order_by(Lower(ordering[1:])).reverse()
            else:
                queryset = queryset.order_by(Lower(ordering))
        return queryset

from django.db.models.functions import Lower only works for Ascending, so basically call .reverse() on it if you need to go Descending.

Answer 3

You can replace the filter function of OrderingFilter , and set the ordering params in Lower :

class CaseInsensitiveOrderingFilter(django_filters.OrderingFilter):
    def filter(self, qs, value):
        if value in django_filters.constants.EMPTY_VALUES:
            return qs

        ordering = [Lower(self.get_ordering_value(param)) for param in value]
        return qs.order_by(*ordering)

Answer 4

use the ordering and ordering_fields arguments in your django-rest list view - http://www.django-rest-framework.org/api-guide/filtering/#specifying-a-default-ordering

class UserListView(generics.ListAPIView):
    queryset = User.objects.all()
    serializer_class = UserSerializer
    filter_backends = (filters.OrderingFilter,)
    ordering_fields = ('username', 'email')
    ordering = ('username',)