Flutter Firestore 错误：DocumentSnapshotPlatform 中不存在字段

Question

我在从 Firestore 读取数据时遇到问题。我想在将用户名存储在 firestore 后在屏幕上显示它。

firestore document

我的代码如下，提前感谢您提供的任何帮助：

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

class Test extends StatefulWidget {
  @override
  _TestState createState() => _TestState();
}

class _TestState extends State<Test> {
  final db = FirebaseFirestore.instance.collection('users').snapshots();

  @override
  Widget build(BuildContext context) {
 
    return Scaffold(
      appBar: AppBar(
        title: Text('Test'),
      ),
body: StreamBuilder<QuerySnapshot>(
        stream: db,
        builder: (context, snapshot) {
          if (!snapshot.hasData) {
            return Center(
              child: CircularProgressIndicator(),
            );
          } else
            return ListView(
              children: snapshot.data!.docs.map((doc) {
                return Card(
                  child: ListTile(
                    title: 
                    // Text(doc.data()['title']),
                    Text(doc.get('First name')
                    
                  ),
                ));
              }).toList(),
            );
        },
      ),

Answer 1

final Stream<DocumentSnapshot<Map<String, dynamic>>> db = FirebaseFirestore.instance
      .collection('users')
      .doc('Personal details')
      .snapshots();

...
body: StreamBuilder<DocumentSnapshot>(
  stream: db,
  builder:
      (BuildContext context, AsyncSnapshot<DocumentSnapshot> snapshot) {
    if (snapshot.hasError) return Text('Something went wrong');
    if (snapshot.connectionState == ConnectionState.waiting)
      return CircularProgressIndicator();

    dynamic data = snapshot.data.data();
    print(data);
    print(data['First name']); // should print 'Guy'
    print(data['Last name']); // should print 'Fang'
    return Text(data['First name']);
  },
),

在您显示的代码中，您正在收听“用户”集合，而不是收听文档“个人详细信息”，如上所示。