无法合并Firestore流

Question

所以，我想这样写查询

... where from = x or to =x 

我找不到有关使用where条件的任何文档。因此，我使用StreamZip

@override
  void initState() {
    getEmail();
    stream1 = databaseReference
        .collection("userChat")
        .where("from", isEqualTo: userId)
        .orderBy("messageDate", descending: true)
        .snapshots();
    stream2 = databaseReference
        .collection("userChat")
        .where('to', isEqualTo: userId)
        .orderBy("messageDate", descending: true)
        .snapshots();
  }

这是我的StreamBuilder

                    StreamBuilder(
                        stream: StreamZip([stream1, stream2]),
                        builder: (context, snapshot) {
                          print(snapshot.data.documents);
                          switch (snapshot.connectionState) {
                            case ConnectionState.none:
                            case ConnectionState.waiting:
                              return Center(
                                child: CircularProgressIndicator(),
                              );
                            default:
                              return new Flexible(
                                child: new ListView.builder(
                                  controller: _scrollController,
                                  padding: new EdgeInsets.all(8.0),
                                  reverse: false,
                                  itemBuilder: (context, index) {
                                    print("Time to show data");
                                    List rev = snapshot
                                        .data.documents.reversed
                                        .toList();
                                    MessageFromCloud messageFromCloud =
                                        MessageFromCloud.fromSnapshot(
                                            rev[index]);
                                    return new ChatMessage(
                                        data: messageFromCloud,
                                        userFullname: userFullname,
                                        userId: userId,
                                        roomId: documentId);
                                  },
                                  itemCount: (messagesCloud != null)
                                      ? messagesCloud.length
                                      : 0,
                                ),
                              );
                          }
                        }),

运行它时，出现此错误

  

“列表”类没有实例获取器“文档”。   收件人：_List len：2尝试调用：文档

我想念什么吗？

Answer 1

StreamZip-发出每个输入流中收集到的值的列表

这意味着您的snapshot.data是一个列表。

建议您查看以下答案：Combine streams from Firestore in flutter