我想问一下是否有任何关于如何在条件语句中比较这两个变量的方法。正如你所看到的，couponSalePriceCtrlr和couponOrigPriceCtrlr。我想验证用户在sale price中的输入不应该大于original price，但似乎validator只接受(value)参数和String数据类型。

Widget editCouponSalePriceWidget(couponSalePriceCtrlr, couponOrigPriceCtrlr) {
  // converted the variable parameters into double data type
  double convertedSalePrice = double.parse(couponSalePriceCtrlr);
  double convertedOrigPrice = double.parse(couponOrigPriceCtrlr);
  return Padding(
    padding: const EdgeInsets.symmetric(horizontal: 0.0),
    child: TextFormField(
      style: const TextStyle(fontFamily: 'Poppins', fontSize: 13),
      controller: couponSalePriceCtrlr,
      keyboardType: TextInputType.number,
      decoration: InputDecoration(
        suffixText: "*",
        suffixStyle: TextStyle(color: Colors.red),
        labelText: 'Sale Price',
        labelStyle: const TextStyle(
            fontSize: 15, fontFamily: 'Poppins', color: Color(0xFF152C4C)),
        isDense: true,
        prefixIcon: const Icon(Icons.person),
        enabledBorder: OutlineInputBorder(
          borderSide: const BorderSide(color: Color(0xFFCECECE)),
          borderRadius: BorderRadius.circular(12),
        ),
        focusedBorder: OutlineInputBorder(
          borderRadius: BorderRadius.circular(12),
          borderSide: const BorderSide(color: Color(0xFFCECECE)),
        ),
        hintText: 'Orig Price',
        fillColor: const Color(0xFFFEFEFE),
        filled: true,
      ),
     // however the validator only accepts, a string data type.
      validator: (convertedSalePrice,convertedOrigPrice) {
        if (convertedSalePrice!.isEmpty ||
            !RegExp(r'[0-9]+[,.]{0,1}[0-9]*').hasMatch(convertedSalePrice)) {
          return "Please enter a valid original price.";
        } else {
          return null;
        }
      },
    ),
  );
}