I want read data from my firestore collection specific document and then the format below as a Map

NEED HELP IN data serialization

Cast Error but Need Data Modeling

**Need Help ** while using stream builder i faced some errors and i can't make them simplified as I need help to understand factory function **because in flutter and dart new upcoming will prefer factory function **

  #String? callerId;
  String? callerName; 
  String? callerPic;
  String? receiverId;
  String? receiverName;
  String? receiverPic;
  String? channelId;
  bool? hasDialled;

  Call({
    this.callerId,
    this.callerName,
    this.callerPic,
    this.receiverId,
    this.receiverName,
    this.receiverPic,
    this.channelId,
    this.hasDialled,
  });

  Map<String, dynamic> toMap(Call call) {
    Map<String, dynamic> callMap = Map();
    callMap["caller_id"] = call.callerId;
    callMap["caller_name"] = call.callerName;
    callMap["caller_pic"] = call.callerPic;
    callMap["receiver_id"] = call.receiverId;
    callMap["receiver_name"] = call.receiverName;
    callMap["receiver_pic"] = call.receiverPic;
    callMap["channel_id"] = call.channelId;
    callMap["has_dialled"] = call.hasDialled;
    return callMap;
  }

  Call.fromMap(Map callMap) {
    this.callerId = callMap["caller_id"];
    this.callerName = callMap["caller_name"];
    this.callerPic = callMap["caller_pic"];
    this.receiverId = callMap["receiver_id"];
    this.receiverName = callMap["receiver_name"];
    this.receiverPic = callMap["receiver_pic"];
    this.channelId = callMap["channel_id"];
    this.hasDialled = callMap["has_dialled"];
  }
}

CollectionReference callcollection =
      FirebaseFirestore.instance.collection(CALL_COLLECTION);
  Stream<DocumentSnapshot> callStream({String? uid}) =>
      callcollection.doc(uid).snapshots();




StreamBuilder<DocumentSnapshot>(
            stream: callMethods.callStream(
                uid: FirebaseAuth.instance.currentUser!.uid),
            builder: (context, snapshot) {
              if (snapshot.hasData && snapshot.data?.data != null) {

 Map<String , dynamic> data = snapshot.data?.data() as Map<String , dynamic>;
    **HERE IS The PROBLEM _CastError (type '_JsonDocumentSnapshot' is not a subtype of type 'Map<String, dynamic>' in type cast)
but i need  data as a map ** 
                Call call = Call.fromMap(data);
               

                if (!call.hasDialled!) {
                  return PickupScreen(call: call);
                }



}

CodePudding user response：

Can you try this:

Map<String , dynamic>? data = snapshot.data?.data() // maybe use null check operator instead of question mark.

or try this:

var data = snapshot.data?.data()

CodePudding user response：

It was just simple Call data = Call( **all key values** ) var data = snapshot.data 'key' :data['place key'] use type be like this for all key values Call call = Call.fromMap(data); not required any more