validateAge function

String? Function(dynamic) validateAge({
  1. int? minAge,
  2. int? maxAge,
  3. String? failMessage,
})

Returns error message if invalid, null if valid.

Implementation

String? Function(dynamic) validateAge({int? minAge, int? maxAge, String? failMessage}) {
  return (dynamic value) {
    if (value == null || value.trim().isEmpty) return null;

    if (!isAge(value, minAge: minAge, maxAge: maxAge)) {
      return failMessage ?? _defaultAgeMessage(minAge, maxAge);
    }
    return null;
  };
}