Flutter/Firebase - List<dynamic> 没有实例 getter 'documents'

Posted 2023-02-23

【中文标题】Flutter/Firebase - List<dynamic> 没有实例 getter \'documents\'

【英文标题】：Flutter/Firebase - List<dynamic> has no instance getter 'documents'Flutter/Firebase - List<dynamic> 没有实例 getter 'documents'

【发布时间】：2020-12-21 09:24:55

【问题描述】：

我正在尝试在我的 Flutter 应用程序中组合两个 Firestore 流。但是，当我尝试实现合并流时，出现以下错误：

    The following NoSuchMethodError was thrown building StreamBuilder<dynamic>(dirty, state: _StreamBuilderBaseState<dynamic, AsyncSnapshot<dynamic>>#25b40):
Class 'List<dynamic>' has no instance getter 'documents'.
Receiver: _List len:2
Tried calling: documents

我假设在建立我的流之前我需要执行另一个步骤，然后才能在页面浏览构建器中使用它？这是我的直播：

Stream<QuerySnapshot> getDefaultOccasions(BuildContext context) async*
  yield* Firestore.instance.collection('datestoremember').document('default').collection('Dates_to_Remember').snapshots();


Stream<QuerySnapshot> getPersonalOccasions(BuildContext context) async*
  final uid = await Provider.of(context).auth.getCurrentUID();
  yield* Firestore.instance.collection('datestoremember').document(uid).collection('Dates_to_Remember').snapshots();


 getData() 
  Stream stream1 = Firestore.instance.collection('datestoremember').document('default').collection('Dates_to_Remember').snapshots();
  Stream stream2 = Firestore.instance.collection('datestoremember').document('Ngrx54m84JbsL0tGvrBeKCBlEnm2').collection('Dates_to_Remember').snapshots();
  return StreamZip([stream1, stream2]);

然后我去这里实现这个：

              child: StreamBuilder(
            stream: getData(),
            builder: (context, snapshot) 
              if(!snapshot.hasData) return const Text("Loading...");
              return new PageView.builder(
                itemCount: snapshot.data.documents.length,
                controller: PageController(viewportFraction: 0.5),
                onPageChanged: (int index) => setState(() => _index = index),
                itemBuilder: (_, i) 
                  return Transform.scale(
                    scale: i == _index ? 1 : 0.5,
                    child: Card(
                      elevation: 6,
                      shape: RoundedRectangleBorder(
                          borderRadius: BorderRadius.circular(10)),
                      child: Column(
                        mainAxisAlignment: MainAxisAlignment.center,
                        children: [
                          Text(snapshot.data.documents[i]['Date'].toDate().day.toString()),
                          Text(DateFormat.MMMM()
                              .format(
                              formatter.parse(snapshot.data.documents[i]['Date'].toDate().toString()))
                              .toString()),
                          Padding(
                            padding: const EdgeInsets.only(
                                left: 8.0, right: 8.0),
                            child: FittedBox(
                              fit: BoxFit.contain,
                              child: Text(
                                snapshot.data.documents[i]['Title'],
                                overflow: TextOverflow.ellipsis,
                              ),
                            ),
                          )
                        ],
                      ),
                    ),
                  );
                ,
              );,
          ),

有什么想法吗？干杯

【参考方案1】：

试试这个：

getData() 
  Stream stream1 = Firestore.instance.collection('datestoremember').document('default').collection('Dates_to_Remember').snapshots();
  Stream stream2 = Firestore.instance.collection('datestoremember').document('Ngrx54m84JbsL0tGvrBeKCBlEnm2').collection('Dates_to_Remember').snapshots();

  return StreamGroup.merge([stream1, stream2]).asBroadcastStream();

使用 StreamZip 编辑：

Stream<List<QuerySnapshot>> getData() 
  Stream stream1 = Firestore.instance.collection('datestoremember').document('default').collection('Dates_to_Remember').snapshots();
  Stream stream2 = Firestore.instance.collection('datestoremember').document('Ngrx54m84JbsL0tGvrBeKCBlEnm2').collection('Dates_to_Remember').snapshots();
  return StreamZip<List<QuerySnapshot>>([stream1, stream2]);

在 StreamBuilder 中：

child: StreamBuilder(
        stream: getData(),
        builder: (BuildContext context, AsyncSnapshot<List<QuerySnapshot>> snapshot) 

          List<QuerySnapshot> combinedSnapshot = snapshot.data.toList();
          combinedSnapshot[0].documents.addAll(combinedSnapshot[1].documents);

          if(!combinedSnapshot[0].hasData) return const Text("Loading...");
          return new PageView.builder(
            itemCount: combinedSnapshot[0].data.documents.length,
            controller: PageController(viewportFraction: 0.5),
            onPageChanged: (int index) => setState(() => _index = index),
            itemBuilder: (_, i) 
              return Transform.scale(
                scale: i == _index ? 1 : 0.5,
                child: Card(
                  elevation: 6,
                  shape: RoundedRectangleBorder(
                      borderRadius: BorderRadius.circular(10)),
                  child: Column(
                    mainAxisAlignment: MainAxisAlignment.center,
                    children: [
                      Text(combinedSnapshot[0].data.documents[i]['Date'].toDate().day.toString()),
                      Text(DateFormat.MMMM()
                          .format(
                          formatter.parse(combinedSnapshot[0].data.documents[i]['Date'].toDate().toString()))
                          .toString()),
                      Padding(
                        padding: const EdgeInsets.only(
                            left: 8.0, right: 8.0),
                        child: FittedBox(
                          fit: BoxFit.contain,
                          child: Text(
                            combinedSnapshot[0].data.documents[i]['Title'],
                            overflow: TextOverflow.ellipsis,
                          ),
                        ),
                      )
                    ],
                  ),
                ),
              );
            ,
          );,
      ),

【讨论】：

感谢鲁本，这消除了我的错误，但合并后似乎一次只显示一个原始流，而不是像我希望的那样合并。任何想法如何解决这个问题？

那么我建议像你以前一样使用 StreamZip 并尝试投射这个 StreamZip。我更新了我的答案。

谢谢，我已经实现了更改，但我现在遇到了一个新错误：type '_MapStream' is not a subtype of type 'Stream> '，有什么想法吗？

也许在你的 Cast 中只用 QuerySnapshot 替换 Stream>

这让我回到我原来的错误：类 'List' 没有实例 getter 'documents'。接收者：_List len:2 尝试调用：文档 -- 不过感谢您的建议