validateIntValue.dart

String? validateIntValue(
  String value,
  String errorMsg, {
  bool positive = false,
  int maxValue = 9223372036854775807,
}) {
  if (value.isEmpty) {
    return errorMsg;
  } else {
    try {
      int i = int.parse(value);

      if (i > maxValue) {
        return errorMsg;
      }

      if (positive && i < 0) {
        return errorMsg;
      }

      return null;
    } catch (e) {
      return errorMsg;
    }
  }
}


String? validateDoubleValue(
  String value,
  String errorMsg, {
  bool positive = false,
  double? maxValue = double.maxFinite,
}) {
  if (value.isEmpty) {
    return errorMsg;
  } else {
    try {
      value = value.replaceFirst(",", ".");
      double d = double.parse(value);

      if (maxValue != null && d > maxValue) {
        return errorMsg;
      }

      if (positive && d < 0) {
        return errorMsg;
      }

      return null;
    } catch (e) {
      return errorMsg;
    }
  }
}