Adding filtering changes ordering

Question

I have a ModelViewSet that I want to add filtering to. My simple model looks like

class Article(models.Model):
    date = = models.DateField()
    language = models.CharField(max_length=10)

    class Meta:
        ordering = ['-date']

And the ModelViewSet (read only):

class ArticleViewSet(viewsets.ReadOnlyModelViewSet):
    queryset = Article.objects.all()
    serializer_class = ArticleSerializer

Articles on the API are now ordered by date descending as I would expect. Now I wich to allow filtering on language. I've set the filter backend to DjangoFilterBackend in settings.py. My updated ModelViewSet now looks like:

class ArticleViewSet(viewsets.ReadOnlyModelViewSet):
    queryset = Article.objects.all()
    serializer_class = ArticleSerializer
    filter_fields = ['language']

This changes the ordering to language ASC. Adding order_by('-date') to queryset does not change anything. Adding ordering = ('-date', ) does not change anything. => How do I specify both filtering and ordering (or simply use default ordering while allowing filtering)?

EDIT: Current functionality seems to come from AutoFilterSet created in Rest Framework by default: https://github.com/tomchristie/django-rest-framework/blob/822eb39599b248c68573c3095639a831ab6df99a/rest_framework/filters.py#L53 ... where order_by=True and the handing of this in django-filter get_ordering_field here: https://github.com/alex/django-filter/blob/d88b98dd2b70551deb9c128b209fcf783b325acc/django_filters/filterset.py#L325

=> Seems I have to create a FilterSet class:

class LanguageFilter(django_filters.FilterSet):
    class Meta:
        model = Article
        fields = ['language']
        order_by = model()._meta.ordering

class ArticleViewSet(viewsets.ReadOnlyModelViewSet):
    queryset = Article.objects.all()
    serializer_class = ArticleSerializer
    filter_class = LanguageFilter

Does this look correct? Seems a bit "much"/verbose to retain default ordering.

Answer 1

Rather than implementing your own FilterSet, you can instead just add an OrderingFilter, specifying an ordering = ['-date'] or better: ordering = Article._meta.ordering on your view, to restore the lost (default) ordering. This would also allow your users to use an ordering query parameter to override your default ordering of results.