import 'package:formz/formz.dart'; enum TransactionDescriptionValidationError { empty('Description empty'), invalid('Description invalid'); final String message; const TransactionDescriptionValidationError(this.message); } class TransactionDescription extends FormzInput { const TransactionDescription.pure() : super.pure(''); const TransactionDescription.dirty([super.value = '']) : super.dirty(); @override TransactionDescriptionValidationError? validator(String value) { return value.isEmpty ? TransactionDescriptionValidationError.empty : null; } }