filter_range_fields = [
        (('min_date', 'max_date'), models.ScheduleD.load_date),
        (('min_payment_period', 'max_payment_period'), models.ScheduleD.payment_period),
        (('min_amount_incurred_period', 'max_amount_incurred_period'), models.ScheduleD.amount_incurred_period),
        (('min_image_number', 'max_image_number'), models.ScheduleD.image_number),