validate method

@override String? validate()

Implementation

@override
String? validate() {
  if(value.isEmpty){
    return null;
  }
  RegExp exp = RegExp(
      r"^(?!0)(?!.*\.$)((1?\d?\d|25[0-5]|2[0-4]\d)(\.|$)){4}$",
      caseSensitive: false,
      multiLine: false);
  if (!exp.hasMatch(value)) {
    return FV.buildMessage(customMessage ?? FV.ip, attribute);
  }
  return null;
}