我一直在尝试使用a StreamBuilder或类似方法收听Firestone的多个收藏。当我仅使用一个Stream时，我的原始代码是：

import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';
import 'package:cloud_firestore/cloud_firestore.dart';

class List extends StatefulWidget{

  ///The reference to the collection is like
  ///Firestore.instance.collection("users").document(firebaseUser.uid).collection("list1").reference()
  final CollectionReference listReference;

  List(this.listReference);

  @override
  State createState() => new ListState();
}

class ListState extends State<List> {

  @override
  Widget build(BuildContext context){

    return new StreamBuilder(
        stream: widget.listReference.snapshots(),
        builder: (context, snapshot) {
          return new ListView.builder(
              itemCount: snapshot.data.documents.length,
              padding: const EdgeInsets.only(top: 2.0),
              itemExtent: 130.0,
              itemBuilder: (context, index) {
                DocumentSnapshot ds = snapshot.data.documents[index];
                return new Data(ds);
              }
          );
        });
  }
}

这段代码可以正常工作，但是现在我想听多个集合。我遇到了一个不涉及StreamBuilder并与动态列表一起使用的解决方案。我的代码现在看起来像这样：

import 'dart:async';
import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';
import 'package:cloud_firestore/cloud_firestore.dart';
import 'main.dart';
import 'package:async/async.dart';

class ListHandler extends StatefulWidget{

  final CollectionReference listReference;

  ListHandler(this.listReference);

  @override
  State createState() => new ListHandlerState();
}

class ListHandlerState extends State<ListHandler> {

  StreamController streamController;
  List<dynamic> dataList = [];

  @override
  void initState() {
    streamController = StreamController.broadcast();
    setupData();
    super.initState();
  }

  @override
  void dispose() {
    super.dispose();
    streamController?.close();
    streamController = null;
  }

  Future<Stream> getData() async{
      Stream stream1 = Firestore.instance.collection("users").document(firebaseUser.uid).collection("list1").snapshots();
      Stream stream2 = Firestore.instance.collection("users").document(firebaseUser.uid).collection("list2").snapshots();

      return StreamZip(([stream1, stream2])).asBroadcastStream();
  }

  setupData() async {
    Stream stream = await getData()..asBroadcastStream();
    stream.listen((snapshot) {
      setState(() {
        //Empty the list to avoid repetitions when the users updates the 
        //data in the snapshot
        dataList =[];
        List<DocumentSnapshot> list;
        for(int i=0; i < snapshot.length; i++){
          list = snapshot[i].documents;
          for (var item in list){
            dataList.add(item);
          }
        }
      });
    });
  }

  @override
  Widget build(BuildContext context){
    if(dataList.length == 0){
      return new Text("No data found");
    }

    return new ListView.builder(
        itemCount: dataList.length,
        padding: const EdgeInsets.only(top: 2.0),
        itemBuilder: (context, index) {
          DocumentSnapshot ds = dataList[index];
          return new Data(ds['title']);
        }
    );
  }
}

问题是ListView返回的Data是a
StatefulWidget，用户可以与它进行交互，从而在Firestore中进行数据更改，从而出现下一个错误：

[VERBOSE-2:dart_error.cc(16)] Unhandled exception:
setState() called after dispose(): ListHandlerState#81967(lifecycle state: defunct, not mounted)
This error happens if you call setState() on a State object for a widget that no longer appears in the widget tree (e.g., whose parent widget no longer includes the widget in its build). This error can occur when code calls setState() from a timer or an animation callback. The preferred solution is to cancel the timer or stop listening to the animation in the dispose() callback. Another solution is to check the "mounted" property of this object before calling setState() to ensure the object is still in the tree.
This error might indicate a memory leak if setState() is being called because another object is retaining a reference to this State object after it has been removed from the tree. To avoid memory leaks, consider breaking the reference to this object during dispose().

该应用程序不会崩溃，它可以完成预期的操作，但始终显示此错误。

有些人使用该库rxdart来处理流，我曾尝试做类似下面的代码的事情，但是当我将其放入StreamBuilder中时，仅包含来自的元素：

import 'dart:async';
import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';
import 'package:cloud_firestore/cloud_firestore.dart';
import 'main.dart';
import 'showInfo.dart';
import 'package:rxdart/rxdart.dart';

class ListHandler extends StatefulWidget{

  @override
  State createState() => new ListHandlerState();
}

class ListHandlerState extends State<ListHandler> {

  Stream getData() {
    Stream stream1 = Firestore.instance.collection("users").document(firebaseUser.uid).collection("list1").snapshots();
    Stream stream2 = Firestore.instance.collection("users").document(firebaseUser.uid).collection("list2").snapshots();

    return Observable.merge(([stream2, stream1]));
  }

  @override
  Widget build(BuildContext context){
    return new StreamBuilder(
        stream: getData(),
        builder: (context, snapshot) {
          if(!snapshot.hasData){
            print(snapshot);
            return new Text("loading");
          }
          return new ListView.builder(
              itemCount: snapshot.data.documents.length,
              padding: const EdgeInsets.only(top: 2.0),
              itemBuilder: (context, index) {
                DocumentSnapshot ds = snapshot.data.documents[index];
                return new Data(ds);
              }
          );
        });
  }
}

这是我第一次使用Streams，但我不太了解它们，我希望您对如何做有想法。