类型“DocumentSnapshot”不是类型“Map <String，dynamic>”的子类型

Question

这是我的个人资料页面，
我还尝试了 snapshot.data() 并尝试通过查看其他一些 StackOverflow 答案将其转换为地图数据。请帮我解决这个问题。

错误出现在第 63 行。我不知道如何纠正。实际上，在教程中，他们显示了来自文档，但我必须使用 FromMap 但我不确定如何使用它

import 'package:flutter/material.dart';
import 'package:cloud_firestore/cloud_firestore.dart';
import 'package:firebase_storage/firebase_storage.dart' as firebase_storage;
import 'package:provider/provider.dart';
import 'package:cached_network_image/cached_network_image.dart';

import 'package:justpoll/screens/profile/edit_profile.dart';
import 'package:justpoll/screens/profile/profile_nav_bar/settings.dart';
import 'package:justpoll/screens/profile/profile_nav_bar/help.dart';
import 'package:justpoll/Constants.dart';
import 'package:justpoll/widgets/progress.dart';
import 'package:justpoll/libmodels/user_model.dart';
import 'package:justpoll/libservices/authentication_service.dart';
import 'package:justpoll/screens/home_page/nav.dart';

class Profile2 extends StatefulWidget {
  final String profileId;

  Profile2({this.profileId});
  @override
  _Profile2State createState() => new _Profile2State();
}

final userRef = FirebaseFirestore.instance.collection("users");

class _Profile2State extends State<Profile2> {
  buildProfileButton() {
    return Text("profile Button");
  }

  Column buildCountColumn(String lable, int count) {
    return Column(
      mainAxisSize: MainAxisSize.min,
      mainAxisAlignment: MainAxisAlignment.center,
      children: [
        Text(
          count.toString(),
          style: TextStyle(fontSize: 22.0, fontWeight: FontWeight.bold),
        ),
        Container(
          margin: EdgeInsets.only(top: 4.0),
          child: Text(
            lable,
            style: TextStyle(
              color: Colors.grey,
              fontSize: 15.0,
              fontWeight: FontWeight.w400,
            ),
          ),
        )
      ],
    );
  }

  buiildProfileHeader() {
    return FutureBuilder(
      future: userRef.doc(widget.profileId).get(),
      builder: (context, snapshot) {
        if (!snapshot.hasData) {
          return circularProgress();
        }

        UserModel user = UserModel.fromMap(snapshot.data.data);

        return Padding(
          padding: EdgeInsets.all(16.0),
          child: Column(
            children: [
              Row(
                children: [
                  CircleAvatar(
                    radius: 40.0,
                    backgroundColor: Colors.grey,
                    backgroundImage: CachedNetworkImageProvider(user.photoUrl),
                  ),
                  Expanded(
                    flex: 1,
                    child: Column(
                      children: [
                        Row(
                          mainAxisSize: MainAxisSize.max,
                          mainAxisAlignment: MainAxisAlignment.spaceEvenly,
                          children: [
                            buildCountColumn("posts", 0),
                            buildCountColumn("follower", 0),
                            buildCountColumn("following", 0),
                          ],
                        ),
                        Row(
                          mainAxisAlignment: MainAxisAlignment.spaceEvenly,
                          children: [
                            buildProfileButton(),
                          ],
                        )
                      ],
                    ),
                  ),
                ],
              ),
              Container(
                alignment: Alignment.centerLeft,
                padding: EdgeInsets.only(top: 12.0),
                child: Text(
                  user.username,
                  style: TextStyle(
                    fontWeight: FontWeight.bold,
                    fontSize: 16.0,
                  ),
                ),
              ),
              Container(
                alignment: Alignment.centerLeft,
                padding: EdgeInsets.only(top: 4.0),
                child: Text(
                  user.name,
                  style: TextStyle(
                    fontWeight: FontWeight.bold,
                  ),
                ),
              ),
              Container(
                alignment: Alignment.centerLeft,
                padding: EdgeInsets.only(top: 2.0),
                child: Text(
                  user.bio,
                ),
              ),
            ],
          ),
        );
      },
    );
  }

  @override
  Widget build(BuildContext context) {
    return new Scaffold(
      appBar: new AppBar(
        iconTheme: IconThemeData(color: MyColors.black),
        backgroundColor: Colors.white,
        actions: [
          Padding(
            padding: const EdgeInsets.all(13.0),
            child: GestureDetector(
              onTap: () {
                Navigator.push(
                  context,
                  MaterialPageRoute(
                    builder: (context) => EditProfile(),
                  ),
                );
              },
              child: Icon(
                Icons.edit,
                color: MyColors.black,
                size: 26,
              ),
            ),
          ),
        ],
      ),
      drawer: new Drawer(
          child: new ListView(
        children: <Widget>[
          new ListTile(
            leading: Icon(Icons.settings),
            title: new Text('Settings'),
            onTap: () {
              Navigator.of(context).push(
                MaterialPageRoute(builder: (context) => SettingsScreen()),
              );
            },
          ),
          new ListTile(
            leading: Icon(Icons.bookmark),
            title: new Text('Bookmarks'),
            onTap: () {},
          ),
          new ListTile(
            leading: Icon(Icons.drafts),
            title: new Text('Drafts'),
            onTap: () {},
          ),
          new ListTile(
            leading: Icon(Icons.archive),
            title: new Text('Archive'),
            onTap: () {},
          ),
          new ListTile(
            leading: Icon(Icons.help),
            title: new Text('help'),
            onTap: () {
              Navigator.of(context).push(
                MaterialPageRoute(builder: (context) => HelpPage()),
              );
            },
          ),
        ],
      )),
      body: ListView(
        children: <Widget>[
          buiildProfileHeader(),
        ],
      ),
    );
  }
}

这是我的用户模块

class UserModel {
  String email;
  String uid;
  String username;
  String name;
  DateTime timestamp;
  bool isPrivate;
  String photoUrl;
  String gender;
  String bio;
  String birthday;
  Map followers;
  Map following;

  UserModel({
    this.email,
    this.uid,
    this.username,
    this.timestamp,
    this.name,
    this.photoUrl,
    this.isPrivate,
    this.gender,
    this.bio,
    this.birthday,
    this.followers,
    this.following,
  });

  Map toMap(UserModel user) {
    var data = Map<String, dynamic>();

    data["uid"] = user.uid;
    data["username"] = user.username;
    data["email"] = user.email;
    data['name'] = user.name;
    data['photoUrl'] = user.photoUrl;
    data["timestamp"] = user.timestamp;
    data["isPrivate"] = user.isPrivate;
    data["gender"] = user.gender;
    data["bio"] = user.bio;
    data["birthday"] = user.birthday;
    data["followers"] = user.followers;
    data["following"] = user.following;
    return data;
  }

  UserModel.fromMap(Map<String, dynamic> mapData) {
    this.uid = mapData["uid"];
    this.username = mapData["username"];
    this.email = mapData["email"];
    this.name = mapData["name"];
    this.isPrivate = mapData["isPrivate"];
    this.gender = mapData["gender"];
    this.photoUrl = mapData["photoUrl"];
    this.bio = mapData["bio"];
    this.birthday = mapData["birthday"];
    this.followers = mapData["followers"];
    this.following = mapData["following"];
  }
}

Answer 1

尝试这个

var DocData = snapshot.data as DocumentSnapshot;

这为您提供了可以通过以下方式访问的数据

DocData['fieldname'];

你可以使用这样的字段