validate method

@override String? validate(dynamic value)

Return an error message if the value is invalid, otherwise return null.

Implementation

@override
String? validate(dynamic value) {
  if(value is! List) {
    if(value is! String) {
      return "Expected value for $name to be a list";
    }
    value = value.split("[ ,]");
  }

  if(findChoice(wildcardValue) == null) {
    for(final textValue in value) {
      final choice = findChoice(textValue);
      if(choice == null) {
        return "$textValue is not a valid choice for $name";
      }
    }
  }
  return null;
}