Flutter - Creating Document Collection from an existing Document Collection Error : path.isNotEmpty

Question

Please help me, i'm new to Firebase and i have a message error when i'm trying to create a collection from an existing collection ID.

The conversation is created and the ChatRoom also but i have the message appearing and disappearing after around 10 secondes, it seems as the second function doesn't wait the first one

Here's the structure :

• Create a document in "Conversations" collection.
• Getting the ID of that document.
• Create a document in "ChatRoom" collection that has the same ID as the document in "Conversations".

Here's the message error :

The following assertion was thrown building chatPage(dirty, state: _chatPageState#e5c15): a document path must be a non-empty string 'package:cloud_firestore/src/collection_reference.dart': Failed assertion: line 59 pos 14: 'path.isNotEmpty'

Here's my code :

class chatPage extends StatefulWidget {
  @override
  _chatPageState createState() => _chatPageState();

  static String conversationId = "";

}

  final CollectionReference conversationRef =
      FirebaseFirestore.instance.collection("Conversations");

Future<String> getConversationID() async {
    //Initialize Conversations collection
    final QuerySnapshot snapshot = await conversationRef.get();
    String convId = "";

    snapshot.docs.forEach((DocumentSnapshot doc) {
      if (doc["NumTel_Parent"] == OTPScreen.numTelParent &&
          doc["Rendu"] == "Null") {
        _isConv = true;
        print("Conversation already Exist");
        convId = doc.id;
      }
    });
    if (_isConv == false) {
      print("Adding conversation ...");
      await bambiDB().addConversation(OTPScreen.numTelParent, "Null", "Null");

      snapshot.docs.forEach((DocumentSnapshot doc1) {
        if (doc1["NumTel_Parent"] == OTPScreen.numTelParent &&
            doc1["Rendu"] == "Null") {
          _isConv = true;
          print("Conversation created");
          convId = doc1.id;
        }
      });
    }
    return convId;
  }

  createChatRoomMessageAuto() async {
      final CollectionReference chatRoomRef = FirebaseFirestore.instance
          .collection("ChatRoom")
          .doc(chatPage.conversationId)
          .collection("ChatRoomParent");

      final QuerySnapshot snapshot = await chatRoomRef.get();

      if (snapshot.docs.length == 0) {
        chatRoomRef.add({
          "Message": messageAuto1,
          "DateMessage": DateTime.now(),
          "Who": "Doctor"
        }).then((_) {
          print("auto1 created");
        }).catchError((_) {
          print("an error occured");
        });

        chatRoomRef.add({
          "Message": messageAuto2,
          "DateMessage": DateTime.now(),
          "Who": "Doctor"
        }).then((_) {
          print("auto2 created");
        }).catchError((_) {
          print("an error occured");
        });

        chatRoomRef.add({
          "Message": messageAuto3,
          "DateMessage": DateTime.now(),
          "Who": "Doctor"
        }).then((_) {
          print("auto3 created");
        }).catchError((_) {
          print("an error occured");
        });

        chatRoomRef.add({
          "Message": messageAuto4,
          "DateMessage": DateTime.now(),
          "Who": "Doctor"
        }).then((_) {
          print("auto4 created");
        }).catchError((_) {
          print("an error occured");
        });
      } else {
        print("Auto already created.");
      }
  }

 void creatingChatRoom() async {
    chatPage.conversationId = "";

    chatPage.conversationId = await getConversationID();

    createChatRoomMessageAuto();

    setState(() {});
  }

 @override
  void initState() {
    // TODO: implement initState
    super.initState();
    creatingChatRoom();
  }

Answer 1

Welcome to SO! I'm having trouble understanding the code fully. It seems like some may be missing, specifically a complete definition of _chatPageState(). As a tip for future questions, you'll generally find it easier to get responses if you can strip the code back to a simplified example where possible.

My first line of thought is: does it work if conversationId is a value inside the _chatPageState instead of being a static property of chatPage?

My second thought is: does it work if you chain the two async functions like this?

getConversationID().then((id) {
    chatPage.conversationId = id;
    createChatRoomMessageAuto();
});

If the latter works, you probably may not even need to store conversationId at all as you might be able to pass it straight through to the createChatRoomMessageAuto function like

getConversationID().then((id) {
    createChatRoomMessageAuto(id);
});

Me playing with a simplified version if it helps