颤振 - Cloud Firestore 0.14 中 Future.builder 的问题答案

【问题标题】：flutter - an issue with Future.builder in Cloud Firestore 0.14颤振 - Cloud Firestore 0.14 中 Future.builder 的问题
【发布时间】：2020-12-14 02:32:06
【问题描述】：

我昨天更新了 Cloud Firestore。而且，我很惊讶关于 Firestore 的一切都出错了。我试图更新我的代码，但我仍然收到 Future builder 的错误。这是代码和错误。更新前代码没问题。

  Future getposts() async{
await Firebase.initializeApp();
var firestore = FirebaseFirestore.instance;
  QuerySnapshot qn = await firestore.collection("Restaurants").get();
  return qn.docs;}


 FutureBuilder(
                    future: getposts(),
                    builder: (_,snapshot){
                      if(snapshot.connectionState == ConnectionState.waiting){
                        return Center(
                          child: CircularProgressIndicator(),
                        );}
                      else{
                        return ListView.builder(
                          itemCount: snapshot.data().length,
                          itemBuilder: (_,index){
                            return Center(
                              child: Text(snapshot.data()[index].data()["name"]),
                            );
                          },);
                      }
                    },
                  ),

════════ 小部件库捕获的异常═══════════════════════════════ ═════════════════════ 在构建 FutureBuilder(dirty, state: _FutureBuilderState#2c7a5) 时引发了以下 NoSuchMethodError：类“列表”没有实例方法“调用”。接收方：“_GrowableList”的实例（长度：2）尝试调用：call()

相关的导致错误的小部件是： FutureBuilder file:///C:/Users/youse/AndroidStudioProjects/new_app/lib/screens/main_page.dart:226:23 抛出异常时，这是堆栈： #0 Object.noSuchMethod (dart:core-patch/object_patch.dart:51:5) #1 _MainPageState.build。（包：new_app/screens/main_page.dart:235:55） #2 _FutureBuilderState.build (package:flutter/src/widgets/async.dart:740:55) #3 StatefulElement.build (package:flutter/src/widgets/framework.dart:4663:28) #4 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:4546:15) ... ══════════════════════════════════════════════════ ══════════════════════════════════════════════════

【问题讨论】：

标签： firebase flutter google-cloud-firestore

【解决方案1】：

感谢您的帮助。我通过删除第一个数据中的括号解决了这个问题。这是正确的代码。

 Future getposts() async{
await Firebase.initializeApp();
var firestore = FirebaseFirestore.instance;
  QuerySnapshot qn = await firestore.collection("Restaurants").get();
  return qn.docs;}

FutureBuilder(
                    future: getposts(),
                    builder: (_,snapshot){
                      if(snapshot.connectionState == ConnectionState.waiting){
                        return Center(
                          child: CircularProgressIndicator(),
                        );}
                      else{
                        return ListView.builder(
                          itemCount: snapshot.data.length,
                          itemBuilder: (_,index){
                            return Center(
                              child: Text(snapshot.data[index].data()["name"]),
                            );
                          },);
                      }
                    },
                  ),

【讨论】：