如何将自定义过滤字段添加到 Django Rest Framework APIListView

Question

I'm using django rest framework and I have a ListAPIView that I would like to implement a complex filtering functionality that I'm using Q filters. My question is how do I generate custom fields for this filtering?

url: path('', EventListView.as_view(), name='event_list_view'),

serializer:

class EventSerializer(serializers.ModelSerializer):
    class Meta:
        model = Event
        exclude = ('user', )

View:

class EventListView(ListAPIView):
    authentication_classes = ()
    permission_classes = ()
    serializer_class = EventSerializer

filter function:

def filter_events(
        user: User, sort_by: int = DISTANCE, privacy_levels: [int] = [EVERYONE], categories: [Category] = None,
        start_date: datetime.datetime = DEFAULT_START_DATE, end_date: datetime.datetime = DEFAULT_END_DATE,
        distance: int = DEFAULT_DISTANCE, current_location: Point = None, unit: int = None,
        clubs: [UniversityClub] = None, universities: [University] = None,
        greeks: [GreekOrganization] = None, groups: [UserGroup] = None, users_p: [User] = None
                  ):
    ....

    if EVERYONE in privacy_levels:
        everyone_q = Q(privacy_level=EVERYONE, university__in=user_universities, start_time__range=[start_date, end_date])
    else:
        everyone_q = Q()
    if STUDENTS in privacy_levels:
        student_q = Q(privacy_level=STUDENTS, start_time__range=[start_date, end_date])
    else:
        student_q = Q()
    ...

Answer 1

I would recommend you to have a look atdjango-filter and DjangoFilterBackend for DRF :

The django-filter library includes a DjangoFilterBackend class which supports highly customizable field filtering for REST framework.

django-filter is very powerful and allows you to define reusable and combinable filters. Example:

class EventFilter(django_filters.FilterSet):
    privacy_level = django_filters.ChoiceFilter(choices=PRIVACY_LEVELS)

    class Meta:
        model = Event

You can also provide your own filtering method if you want to implement custom filtering logic:

class EventFilter(django_filters.FilterSet):
    privacy_level = django_filters.ChoiceFilter(choices=PRIVACY_LEVELS, method='filter_privacy_level')

    def filter_privacy_level(self, queryset, name, value):
        # Filter upon given privacy level
        queryset = queryset.filter(privacy_level=value)

        # Apply your custom logic given the privacy_level
        if value == UNIVERSITY:
            queryset = queryset.filter(another_field='foo')

        return queryset            

    class Meta:
        model = Event

The beauty behind this is that each Filter will return a queryset ; which allows django-filter to chain them and thus to allow any combinations of filters.

However, in your specific case, you'll need the current user in your filter method. We can also do that by customizing the DjangoFilterBackend :

class UserFilterBackend(filters.DjangoFilterBackend):
    def get_filterset_kwargs(self, request, queryset, view):
        # Get the default constructor kwargs
        kwargs = super().get_filterset_kwargs(request, queryset, view)

        # Add the current user in it
        kwargs['user'] = request.user

        return kwargs


class EventFilter(django_filters.FilterSet):
    privacy_level = django_filters.ChoiceFilter(choices=PRIVACY_LEVELS, method='filter_privacy_level')

    # Overload the default constructor to retrieve the user in kwargs
    def __init__(self, *args, user=None, **kwargs):
        super().__init__(*args, **kwargs)
        # Keep the user in the filter instance
        self.user = user

    def filter_privacy_level(self, queryset, name, value):
        # Filter upon given privacy level
        queryset = queryset.filter(privacy_level=value)

        # Apply your custom logic given the privacy_level
        if value == UNIVERSITY:
            # Great, we can retrieve the user universities!
            queryset = queryset.filter(university__in=self.user.universities)

        return queryset            

    class Meta:
        model = Event

Of course, you should now use your UserFilterBackend instead of filters.DjangoFilterBackend in the filter_backends of your viewset.