flutter - 后台接收数据时如何将数据保存到Hive数据库中？

Question

当应用在后台时接收 Firebase Cloud Messaging (FCM) 推送通知数据时，我在将数据保存到 Hive 时遇到问题。

我有一个静态方法来像这样设置配置单元

static Future<void> setUpHive() async {
    try {

      await Hive.initFlutter();

      if (!Hive.isBoxOpen("Box Name")) {
          await Hive.openBox("Box Name");
      }

    } catch (error) {
      print(error.toString());
    }
}

我在 main 函数中使用 setUpHive 静态方法，如下所示

Future<void> main() async {

  await HiveHelper.setUpHive();

  runApp(
    MyApp(),
  );
}

当应用程序在后台时，然后它收到FCM消息，那么下面的代码将被调用。之后我尝试更改存储在 Hive 框中的数据

Future<void> firebaseMessagingBackgroundHandler(RemoteMessage message) async {
    // when receive FCM message when app is in the background, this block will be executed
    
    // set up the hive first
    await HiveHelper.setUpHive(); 

    // then I try to change the data stored in the Hive box
    final myBox = Hive.box("BOX NAME");
    myBox.put("key", 12345);
}

收到 FCM 后台数据后似乎没问题，但是当我完全关闭应用程序并再次调用 main 时，尝试打开这样的框时出现错误

   static Future<void> setUpHive() async {
        try {

          await Hive.initFlutter();

          if (!Hive.isBoxOpen("Box Name")) {
              await Hive.openBox("Box Name"); // Error in this line
          }

        } catch (error) {
          print(error.toString());
        }
    }

错误是:

HiveError: This should not happen. Please open an issue on GitHub. E/flutter (13142): [ERROR:flutter/lib/ui/ui_dart_state.cc(199)] Unhandled Exception: HiveError: This should not happen. Please open an issue on GitHub. E/flutter (13142): #0 BinaryReaderImpl.readFrame (package:hive/src/binary/binary_reader_impl.dart:250:7) E/flutter

我尝试寻找解决方案，并从here about Using Hive DB in a Background Process中发现类似的问题据说

leisim:

Unfortunately, Hive does not support opening boxes in multiple isolates. That means you can either close the box in the main isolate, update it in your background isolate and reopen it in the main isolate or you pass the data from the background to the main isolate and perform the update there...

我是Flutter新手，不太明白他说的是什么。请帮忙:(

Answer 1

您可以尝试以下代码。基本思想是将数据从后台isolate发送到主isolate。

Future<void> backgroundMessageHandler(RemoteMessage msg){
  IsolateNameServer.lookupPortByName('main_port')?.send(msg);
}

@override
void initState(){
  super.initState();

  ReceivePort receivePort = ReceivePort();
  IsolateNameServer.registerPortWithName(receivePort.sendPort,'main_port');

  receivePort.listen((message) {
    if(message is RemoteMessage){
      //TODO: save your data in hive box
    }
  }
    
}