def queryset(self, request, queryset):
        """Filter queryset using params from the form."""
        if self.form.is_valid():
            # get no null params
            filter_params = dict(
                filter(lambda x: bool(x[1]), self.form.cleaned_data.items())
            )
            return queryset.filter(**filter_params)
        return queryset
Filter queryset using params from the form.