将Firestore文档转换为对象映射

dependencies:
  flutter:
    sdk: flutter
  cloud_firestore: ^3.1.5  # 请检查最新版本

class User {
  final String id;
  final String name;
  final String email;

  User({required this.id, required this.name, required this.email});

  // 从 Firestore 文档创建 User 对象
  factory User.fromFirestore(Map<String, dynamic> data, String documentId) {
    return User(
      id: documentId,
      name: data['name'] ?? '',
      email: data['email'] ?? '',
    );
  }

  // 将 User 对象转换为 Map，用于存储到 Firestore
  Map<String, dynamic> toFirestore() {
    return {
      'name': name,
      'email': email,
    };
  }
}

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

class UserService {
  final FirebaseFirestore _firestore = FirebaseFirestore.instance;

  // 获取用户列表
  Future<List<User>> getUsers() async {
    QuerySnapshot snapshot = await _firestore.collection('users').get();
    return snapshot.docs.map((doc) {
      return User.fromFirestore(doc.data() as Map<String, dynamic>, doc.id);
    }).toList();
  }
}

class UserListScreen extends StatelessWidget {
  final UserService userService = UserService();

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('用户列表')),
      body: FutureBuilder<List<User>>(
        future: userService.getUsers(),
        builder: (context, snapshot) {
          if (snapshot.connectionState == ConnectionState.waiting) {
            return Center(child: CircularProgressIndicator());
          } else if (snapshot.hasError) {
            return Center(child: Text('发生错误: ${snapshot.error}'));
          } else if (!snapshot.hasData || snapshot.data!.isEmpty) {
            return Center(child: Text('没有用户'));
          }

          final users = snapshot.data!;

          return ListView.builder(
            itemCount: users.length,
            itemBuilder: (context, index) {
              final user = users[index];
              return ListTile(
                title: Text(user.name),
                subtitle: Text(user.email),
              );
            },
          );
        },
      ),
    );
  }
}