validate method

@override String? validate()

Implementation

@override
String? validate() {
  if(value.isEmpty){
    return null;
  }
  final parsedExtra = num.tryParse(extra);
  if (parsedExtra == null) {
    return FV.buildMessage(FV.numeric, attribute);
  }

  if (value.length > parsedExtra) {
    return FV.buildMessage(customMessage ?? FV.max, attribute, extra);
  }
  return null;
}