validate method

  1. @override
String? validate(
  1. String valueToValidate
)
override

A function that returns an error message string to display if the input s not pass a validation test and returns null otherwise.

Implementation

@override
String? validate(String valueToValidate) =>
    valueToValidate.contains(RegExp("(?:[A-Z])"))
        ? null
        : "Please enter a value that contains uppercase letters.";