我试图显示我在名为“练习”的 Cloud Firestore 数据库中获取的资料的 ListView：

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

void main() async {
  WidgetsFlutterBinding.ensureInitialized();
  await Firebase.initializeApp();
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  final db = FirebaseFirestore.instance;
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: StreamBuilder<QuerySnapshot>(
        stream: db.collection('Exercises').snapshots(),
        builder: (context, snapshot) {
          if (!snapshot.hasData) {
            return Center(
              child: CircularProgressIndicator(),
            );
          } else
            return ListView(
              children: (snapshot.data! as QuerySnapshot).docs.map((doc) {
                return Card(
                  child: ListTile(
                    title: Text(doc.data()['name']),
                  ),
                );
              }).toList(),
            );
        },
      ),
    );
  }
}

但是当我这样做时，我的应用程序 中出现错误：错误影像

谢谢您的帮助

uj5u.com热心网友回复：

不能直接使用 StreamBuilder 到脚手架，添加 Column 或者 SinglechildScrollview 或者 Container。

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

void main() async {
  WidgetsFlutterBinding.ensureInitialized();
  await Firebase.initializeApp();
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  final db = FirebaseFirestore.instance;
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Column(  // Column, Singlechild Scroll view Here
        children: [
          StreamBuilder<QuerySnapshot>(
            stream: db.collection('Exercises').snapshots(),
            builder: (context, snapshot) {
              if (!snapshot.hasData) {
                return Center(
                  child: CircularProgressIndicator(),
                );
              } else
                return ListView(
                  children: (snapshot.data! as QuerySnapshot).docs.map((doc) {
                    return Card(
                      child: ListTile(
                        title: Text(doc.data()['name']),
                      ),
                    );
                  }).toList(),
                );
            },
          ),
        ],
      ),
    );
  }
}

uj5u.com热心网友回复：

首先感谢您的回答。我用 Column 和 SinglechildScrollview 尝试过，但后来我得到另一个错误，即缺少 MediaQuery 小部件

媒体查询错误