无法从Firestore提取数据

Question

database structure screenshot我正在构建配置文件屏幕，并尝试使用streambuilder从Firestore中的数据库中提取每个用户的名称。但是，我的代码似乎不是从firestore数据库中提取的，并且我仍然得到与以前硬编码相同的名称（每次运行代码时）。下面是我的代码（实际代码中没有错误）。如何修改我的代码，以便实际上可以从Firestore数据库中读取代码？

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

void main() => runApp(new MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return new MaterialApp(
      title: 'Profile Demo',
      theme: new ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: new MyHomePage(title: 'Profile'),
    );
  }
}

class ProfileWidget extends StatelessWidget {
  final String userId;

  ProfileWidget(this.userId);

  @override
  Widget build(BuildContext context) {
    return StreamBuilder<DocumentSnapshot>(
        stream:
        Firestore.instance.collection('users').document(userId).snapshots(),
        builder: (context, snapshot) {
          if (snapshot.hasData) {
            debugPrint('the snapshot name is:'+ snapshot.data['name']);
            User user = User.fromSnapshot(snapshot.data);
            return Row(
                children: <Widget>[Text(snapshot.data['name'].toString())]);
          } else {
            return CircularProgressIndicator();
          }
        });
  }
}

class User {
  final int name;
  final DocumentReference reference;

  User.fromMap(Map<String, dynamic> map, {this.reference}) : name = map['name'];

  User.fromSnapshot(DocumentSnapshot snapshot)
      : this.fromMap(snapshot.data, reference: snapshot.reference);
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key key, this.title}) : super(key: key);
  final String title;

  @override
  _MyHomePageState createState() => new _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  @override
  Widget build(BuildContext context) {
    final _width = MediaQuery.of(context).size.width;
    final _height = MediaQuery.of(context).size.height;
    final String imgUrl =
        'https://pixel.nymag.com/imgs/daily/selectall/2017/12/26/26-eric-schmidt.w700.h700.jpg';

    return new Stack(
      children: <Widget>[
        new Container(
          color: Colors.blue,
        ),
        new Image.network(
          imgUrl,
          fit: BoxFit.fill,
        ),
        new BackdropFilter(
            filter: new ui.ImageFilter.blur(
              sigmaX: 6.0,
              sigmaY: 6.0,
            ),
            child: new Container(
              decoration: BoxDecoration(
                color: Colors.blue.withOpacity(0.9),
                borderRadius: BorderRadius.all(Radius.circular(50.0)),
              ),
            )),
        new Scaffold(
            appBar: new AppBar(
              title: new Text(widget.title),
              centerTitle: false,
              elevation: 0.0,
              backgroundColor: Colors.transparent,
            ),
            drawer: new Drawer(
              child: new Container(),
            ),
            backgroundColor: Colors.transparent,
            body: new Center(
              child: new Column(
                children: <Widget>[
                  new SizedBox(
                    height: _height / 12,
                  ),
                  new CircleAvatar(
                    radius: _width < _height ? _width / 4 : _height / 4,
                    backgroundImage: NetworkImage(imgUrl),
                  ),
                  new SizedBox(
                    height: _height / 25.0,
                  ),
                  new Text(
                    'Eric Schmidt',
                    style: new TextStyle(
                        fontWeight: FontWeight.bold,
                        fontSize: _width / 15,
                        color: Colors.white),
                  ),
                  new Padding(
                    padding: new EdgeInsets.only(
                        top: _height / 30, left: _width / 8, right: _width / 8),
                    child: new Text(
                      'Snowboarder, Superhero and writer.\nSometime I work at google as Executive Chairman ',
                      style: new TextStyle(
                          fontWeight: FontWeight.normal,
                          fontSize: _width / 25,
                          color: Colors.white),
                      textAlign: TextAlign.center,
                    ),
                  ),
                  new Divider(
                    height: _height / 30,
                    color: Colors.white,
                  ),
                  new Row(
                    children: <Widget>[
                      rowCell(343, 'POSTS'),
                      rowCell(673826, 'FOLLOWERS'),
                      rowCell(275, 'FOLLOWING'),
                    ],
                  ),
                  new Divider(height: _height / 30, color: Colors.white),
                  new Padding(
                    padding: new EdgeInsets.only(
                        left: _width / 8, right: _width / 8),
                    child: new FlatButton(
                      onPressed: () {},
                      child: new Container(
                          child: new Row(
                            mainAxisAlignment: MainAxisAlignment.center,
                            children: <Widget>[
                              new Icon(Icons.person),
                              new SizedBox(
                                width: _width / 30,
                              ),
                              new Text('FOLLOW')
                            ],
                          )),
                      color: Colors.blue[50],
                    ),
                  ),
                ],
              ),
            ))
      ],
    );
  }

  Widget rowCell(int count, String type) => new Expanded(
      child: new Column(
        children: <Widget>[
          new Text(
            '$count',
            style: new TextStyle(color: Colors.white),
          ),
          new Text(type,
              style: new TextStyle(
                  color: Colors.white, fontWeight: FontWeight.normal))
        ],
      ));
}