validate method

@override ValidationException? validate(Object? value)

Return null if valid, otherwise a ValidationException.

Implementation

@override
ValidationException? validate(Object? value) {
  if (value is! String) {
    return ValidationException(this, value);
  }

  final len = value.length;

  if (min != null) {
    if (inclusive ? len < min! : len <= min!) {
      return ValidationException(this, value);
    }
  }

  if (max != null) {
    if (inclusive ? len > max! : len >= max!) {
      return ValidationException(this, value);
    }
  }

  return null;
}