[Isolate] Null check operator used on a null value

[bhanuka96]

I tried to implement isolate to update firestore database. But I got Null check operator error. Can't firebase use on secondary isolate?

Error

I/flutter ( 9135): [Null check operator used on a null value, #0      MethodChannel.binaryMessenger (package:flutter/src/services/platform_channel.dart:142:86)
I/flutter ( 9135): #1      MethodChannel._invokeMethod (package:flutter/src/services/platform_channel.dart:148:36)
I/flutter ( 9135): #2      MethodChannel.invokeMethod (package:flutter/src/services/platform_channel.dart:331:12)
I/flutter ( 9135): #3      MethodChannel.invokeListMethod (package:flutter/src/services/platform_channel.dart:344:41)
I/flutter ( 9135): #4      MethodChannelFirebase._initializeCore (package:firebase_core_platform_interface/src/method_channel/method_channel_firebase.dart:30:37)
I/flutter ( 9135): #5      MethodChannelFirebase.initializeApp (package:firebase_core_platform_interface/src/method_channel/method_channel_firebase.dart:77:13)
I/flutter ( 9135): #6      Firebase.initializeApp (package:firebase_core/src/firebase.dart:42:47)
I/flutter ( 9135): #7      Worker.readUpdate (package:yello/services/chatMessageService.dart:202:20)
I/flutter ( 9135): #8      Worker._isolateEntry.<anonymous closure> (package:yello/services/chatMessageService.dart:214:15)
I/flutter ( 9135): #9      Worker._isolateEntry.<anon
I/chatty  ( 9135): uid=10206(u0_a206) 1.ui identical 1 line
I/flutter ( 9135): [Null check operator used on a null value, #0      MethodChannel.binaryMessenger (package:flutter/src/services/platform_channel.dart:142:86)
I/flutter ( 9135): #1      MethodChannel._invokeMethod (package:flutter/src/services/platform_channel.dart:148:36)
I/flutter ( 9135): #2      MethodChannel.invokeMethod (package:flutter/src/services/platform_channel.dart:331:12)
I/flutter ( 9135): #3      MethodChannel.invokeListMethod (package:flutter/src/services/platform_channel.dart:344:41)
I/flutter ( 9135): #4      MethodChannelFirebase._initializeCore (package:firebase_core_platform_interface/src/method_channel/method_channel_firebase.dart:30:37)
I/flutter ( 9135): #5      MethodChannelFirebase.initializeApp (package:firebase_core_platform_interface/src/method_channel/method_channel_firebase.dart:77:13)
I/flutter ( 9135): #6      Firebase.initializeApp (package:firebase_core/src/firebase.dart:42:47)
I/flutter ( 9135): #7      Worker.readUpdate (package:yello/services/chatMessageService.dart:202:20)
I/flutter ( 9135): #8      Worker._isolateEntry.<anonymous closure> (package:yello/services/chatMessageService.dart:214:15)
I/flutter ( 9135): #9      Worker._isolateEntry.<anon

Full Code

class Worker {
  SendPort _sendPort;

  Isolate _isolate;

  final _isolateReady = Completer<void>();

  Worker() {
    init();
  }

  Future<void> get isReady => _isolateReady.future;

  void dispose() {
    _isolate.kill();
  }

  Future<void> fetch(ChatModel model) async {
    _sendPort.send(model);
  }

  Future<void> init() async {
    final receivePort = ReceivePort();
    final errorPort = ReceivePort();
    errorPort.listen(print);

    receivePort.listen(_handleMessage);
    _isolate = await Isolate.spawn(
      _isolateEntry,
      receivePort.sendPort,
      onError: errorPort.sendPort,
    );
  }

  void _handleMessage(dynamic message) {
    if (message is SendPort) {
      _sendPort = message;
      _isolateReady.complete();
      return;
    }

    if (message is bool) {
      return;
    }

    throw UnimplementedError("Undefined behavior for message: $message");
  }

  static Future<void> readUpdate(ChatModel model) async {
    await Firebase.initializeApp();
    final FirebaseFirestore _db = FirebaseFirestore.instance;
    return _db.collection('chats').doc(model.chatFieldId).collection('messages').doc(model.messageId).update({'readStatus': 'R'});
  }

  static void _isolateEntry(dynamic message) {
    SendPort sendPort;
    final receivePort = ReceivePort();

    receivePort.listen((dynamic message) async {
      assert(message is ChatModel);
      try {
        await readUpdate(message);
        sendPort.send(true);
      } finally {
        //client.close();
      }
    });

    if (message is SendPort) {
      sendPort = message;
      sendPort.send(receivePort.sendPort);
      return;
    }
  }
}

[BernardinD]

Similar issue with me. Any progress?

[dsemama]

Same here.

[yadavkhushwant]

I am facing the same issue