关于filter的用法

from rest_framework.filters import BaseFilterBackend

class MenuFilterBackend(BaseFilterBackend):
    def filter_queryset(self, request, queryset, view):

        if request.method == "DELETE":
            return queryset

        folder = request.query_params.get("folder")
        if not folder:
            return queryset.none()
        return queryset.filter(folder_id=folder)


class MenuModelSerializer(serializers.ModelSerializer):
    class Meta:
        model = models.Menu
        fields = ["id", "title", 'name', "folder"]


class MenuView(BaseView, ModelViewSet):
    authentication_classes = [JwtAuthentication]
    permission_classes = [RbacPermission]
    filter_backends = [MenuFilterBackend, ]

    queryset = models.Menu.objects.all().order_by("-id")
    serializer_class = MenuModelSerializer