validateValue method

  1. @override
String? validateValue(
  1. T valueCandidate
)
override

Validates the value. Returns null if the value is valid, otherwise an error message. Call validate() instead of this method when using the validator.

Implementation

@override
String? validateValue(T valueCandidate) {
  return values.where((T element) => element == valueCandidate).length != 1
      ? errorText
      : null;
}