database.dart

static Future<void> addItem({
  required String title,
  required String description,
}) async {
  DocumentReference documentReferencer =
      _mainCollection.doc(userUid).collection('items').doc();

  Map<String, dynamic> data = <String, dynamic>{
    "title": title,
    "description": description,
  };

  await documentReferencer
      .set(data)
      .whenComplete(() => print("Notes item added to the database"))
      .catchError((e) => print(e));
}