断言失败：第 310 行 pos 10：'data != null'：在 onResume 中处理 FCM 消息时出错：回调 Flutter

Question

我有一个方法，在 3 个 firebase 回调中调用，它处理消息并显示两个不同的底部工作表，具体取决于 message['data] 是否具有自定义参数，以显示消息并执行一些操作逻辑..

当应用程序在前台接收消息时，一切都按预期工作，而当我在应用程序在后台接收消息时，点击横幅时出现 Failed assertion: line 310 pos 10: 'data != null': A non null String must be provided to a Text Widget. 错误。

这是为什么？传递给 onLaunch: 和 onResume: 回调的消息不一样？

非常感谢。

消息处理方法：

void handleMessage(Map<String, dynamic> message) {
      if (message['data'].containsKey('isPromotion')) {
        print('on message is promotion message');
        final dynamic notification = message['notification'];
        final dynamic data = message['data'];
        Item item = Item(
          itemId: '${data['promotionId']}',
          brand: '${data['brand']}',
          itemName: '${data['productName']}',
          category: '${data['productCategory']}',
          price: '${data['price']}',
          description: '${data['description']}',
          vendor: '${data['vendor']}',
          code: '${data['barcode']}',
          isPromotion: true,
          imageUrl: '${data['imageUrl']}',
        );

        if (Platform.isIOS) {
          showCupertinoModalPopup(
            context: context,
            builder: (modal) => PushNotificationDataBottomSheetIos(
                onPressed: (){
                  BlocProvider.of<CartBloc>(context)
                      .add(AddItem(item));
                  Navigator.push(context, MaterialPageRoute(
                      builder: (_) => PaymentScreen(
                        bgImage: paymentScreenBgImage,
                        user: widget.user,
                        fcmToken: _token,
                        cityDb: cityDb,
                        regionDb: regionDb,
                        countryDb: countryDb,
                        selectedShop: '${data['vendor']}',
                        isBuyNow: true,
                      )
                  ));
                },
                title: notification['title'],
                body: notification['body']),
          );
        }
        else {
          //Android
          showModalBottomSheet(
            context: context,
            builder: (modal) => PushNotificationDataBottomSheetAndroid(
                onPressed: (){
                  BlocProvider.of<CartBloc>(context)
                      .add(AddItem(item));
                  Navigator.push(context, MaterialPageRoute(
                      builder: (_) => PaymentScreen(
                        bgImage: paymentScreenBgImage,
                        user: widget.user,
                        fcmToken: _token,
                        cityDb: cityDb,
                        regionDb: regionDb,
                        countryDb: countryDb,
                        selectedShop: '${data['vendor']}',
                        isBuyNow: true,
                      )
                  ));
                },
                title: notification['title'],
                body: notification['body']),
          );
        }
      }
      else {
        print('on message is notification message');
        // Handle notification message
        final dynamic notification = message['notification'];
        if (Platform.isIOS) {
          showCupertinoModalPopup(
              context: context,
              builder: (modal) => PushNotificationMessageBottomSheetIos(
                  title: notification['title'],
                  body: notification['body'])
          );
        }
        else {
          //Android
          showModalBottomSheet(
            context: context,
            builder: (modal) => PushNotificationMessageBottomSheetAndroid(
                title: notification['title'],
                body: notification['body']),
          );
        }


      }
    }

firebase 消息配置：

_firebaseMessaging.configure(
      onMessage: (Map<String, dynamic> message) async {
        print('on message $message');
        handleMessage(message);
      },
//      onBackgroundMessage: myBackgroundMessageHandler,
      onResume: (Map<String, dynamic> message) async {
        print('on resume $message');
        handleMessage(message);
      },
      onLaunch: (Map<String, dynamic> message) async {
        print('on launch $message');
        handleMessage(message);
      },
    );
``

Answer 1

好的，我发现，当应用程序在后台并且用户点击横幅时 onResume: 回调被调用，但是 message 地图在那种情况下没有 notification参数.. 这是为什么？？我觉得那一点意义都没有..但是嘿..我不工作 Google 所以..

所以我所做的是将 title 和 body 也添加到 POST 请求中的 'data':，并创建了第二个方法，该方法从 'data': title 和 body 从 onResume: 和 onLaunch:.

调用

但话又说回来..我还更改了第一种方法，从'data':读取title和body，这样我就可以使用一个始终有效的方法..

所以现在我还在犹豫使用 'notification': 有什么意义？

void handleMessage(Map<String, dynamic> message) {
      if (message['data'].containsKey('isPromotion')) {
        print('on message is promotion message');
        final dynamic notification = message['notification'];
        final dynamic data = message['data'];
        Item item = Item(
          itemId: '${data['promotionId']}',
          brand: '${data['brand']}',
          itemName: '${data['productName']}',
          category: '${data['productCategory']}',
          price: '${data['price']}',
          description: '${data['description']}',
          vendor: '${data['vendor']}',
          code: '${data['barcode']}',
          isPromotion: true,
          imageUrl: '${data['imageUrl']}',
        );

        if (Platform.isIOS) {
          showCupertinoModalPopup(
            context: context,
            builder: (modal) => PushNotificationDataBottomSheetIos(
                onPressed: (){
                  BlocProvider.of<CartBloc>(context)
                      .add(AddItem(item));
                  Navigator.push(context, MaterialPageRoute(
                      builder: (_) => PaymentScreen(
                        bgImage: paymentScreenBgImage,
                        user: widget.user,
                        fcmToken: _token,
                        cityDb: cityDb,
                        regionDb: regionDb,
                        countryDb: countryDb,
                        selectedShop: '${data['vendor']}',
                        isBuyNow: true,
                      )
                  ));
                },
//                title: notification['title'],
//                body: notification['body']),
              title: data['title'],
              body: data['body']),
          );
        }
        else {
          //Android
          showModalBottomSheet(
            context: context,
            builder: (modal) => PushNotificationDataBottomSheetAndroid(
                onPressed: (){
                  BlocProvider.of<CartBloc>(context)
                      .add(AddItem(item));
                  Navigator.push(context, MaterialPageRoute(
                      builder: (_) => PaymentScreen(
                        bgImage: paymentScreenBgImage,
                        user: widget.user,
                        fcmToken: _token,
                        cityDb: cityDb,
                        regionDb: regionDb,
                        countryDb: countryDb,
                        selectedShop: '${data['vendor']}',
                        isBuyNow: true,
                      )
                  ));
                },
//                title: notification['title'],
//                body: notification['body']),
              title: data['title'],
              body: data['body']),
          );
        }
      }
      else {
        print('on message is notification message');
        // Handle notification message
        final dynamic notification = message['notification'];
        final dynamic data = message['data'];
        if (Platform.isIOS) {
          showCupertinoModalPopup(
              context: context,
              builder: (modal) => PushNotificationMessageBottomSheetIos(
//                  title: notification['title'],
//                  body: notification['body'])
              title: data['title'],
              body: data['body']),
          );
        }
        else {
          //Android
          showModalBottomSheet(
            context: context,
            builder: (modal) => PushNotificationMessageBottomSheetAndroid(
//                title: notification['title'],
//                body: notification['body']),
              title: data['title'],
              body: data['body']),
          );
        }


      }
    }

断言失败：第 310 行 pos 10：'data != null'：在 onResume 中处理 FCM 消息时出错：回调 Flutter

Failed assertion: line 310 pos 10: 'data != null' : error when handling FCM message in onResume: callback Flutter

flutter

firebase-cloud-messaging

消息处理方法：

firebase 消息配置：