Unidentified Name Error while using required.this value-CodePudding

So Iam trying to make a chat-app using Firebase-Firestore where you have an option of creating group. Now after creating a group Iam navigating to a screen from where you can add member. But for that I gonna need to pass the groupRoomId.

Here Iam navigating to add member screen:

 Navigator.push(
        context,
        MaterialPageRoute(
            builder: (context) => Add_Member(
              groupRoomId: groupRoomId,
            )));

Now here is my add member screen:

class Add_Member extends StatefulWidget {
  final String groupRoomId;
  Add_Member({required this.groupRoomId});
  _Add_Member createState() => _Add_Member();
}

class _Add_Member extends State<Add_Member> {
  QuerySnapshot<Map<String, dynamic>>? searchResultSnapshot;
  QuerySnapshot<Map<String, dynamic>>? Snapshot;
  bool isLoading = false;
  bool haveUserSearched = false;
  bool isChecked = false;
  DatabaseMethods databaseMethods = new DatabaseMethods();
  var searchEditingController = TextEditingController();
  final DocumentReference <Map<String, dynamic>>? documentReference = FirebaseFirestore.instance.doc("groups/$groupRoomId");

addremovemember(userName){
    documentReference?.snapshots().listen((datasnapshot){
      if (datasnapshot.data()!.containsValue("$userName")){
        FirebaseFirestore.instance
            .collection('groups')
            .doc('$groupRoomId')
            .update({"users" : FieldValue.arrayRemove(["$userName"])});
      }
      else{
        FirebaseFirestore.instance
            .collection('groups')
            .doc('$groupRoomId')
            .update({"users" : FieldValue.arrayUnion(["$userName"])});
      }
    });
  }
......

So what is happening that in DocumentReference $groupRoomId is showing Unidentified Name Error. My ultimate aim is to being able to add and remove error(in future too) as you may see in addremovemember function. I would highly appreciable if you can help me.

CodePudding user response：

It happens so because you are referencing groupRoomId which is outside the build scope.

For this to work use the keyword widget

Navigator.push(
        context,
        MaterialPageRoute(
            builder: (context) => Add_Member(
              groupRoomId: widget.groupRoomId,// <-here
            )));

CodePudding user response：

@Davis is right. You are referencing groupRoomId which is outside the build scope.

For this to work, access it using the widget keyword.

Replace .doc('$groupRoomId') with .doc(widget.groupRoomId)