isUpperCase method Null safety
- {String message = "Validator.isUpperCase"}
Returns a Validator that accepts a value where all letters are upper-case.
TODO: Check whether there is a better way to validate this.
Implementation
Validator isUpperCase({
String message = "Validator.isUpperCase",
}) {
return add(
(value) => value == value?.toUpperCase() ? null : message,
);
}