Dart Null Helper Demo

main.dart

void main() {
  // Can return null item
  var item = getItem(true);
  print(emptyIfNull(item?.name)); // Prints "empty"
  
  var notNull = getItem(false);
  print(emptyIfNull(notNull?.name)); // Prints "Hello!"
}

// Demo class
class MyItem {
  String? name;
}

// Helper to get either an item or null.
MyItem? getItem(bool returnNull) {
  if (returnNull) {
    return null;
  }
  var item = MyItem();
  item.name = "Hello!";
  return item;
}

// Helper function to change null into string.
String emptyIfNull(String? item) {
  if (item != null) {
    return item;
  }
  return "empty";
}