Django filter for not null

Question

I have a filter defined as such:

class MessageFilterSet(filters.FilterSet):
    seen = filters.BooleanFilter(field_name="seen_at", lookup_expr="isnull")

And it sort of works. But it's the wrong way around, passing seen=True will return all the unseen messages.

I don't want to have to change the name of the url parameter, how do I invert the lookup expression?

Answer 1

Try this:

class MessageFilterSet(filters.FilterSet):
    seen = filters.BooleanFilter(field_name="seen_at", lookup_expr="isnull", exclude = True)

From Django Filter Reference Docs:

exclude

A boolean that specifies whether the Filter should use filter or exclude on the queryset. Defaults to False.