如何在flutter中获取firestore中的最后一个文档id？

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

class FirestoreExample extends StatelessWidget {
  Future<String> getLastDocumentId() async {
    // 初始化Firebase App
    await Firebase.initializeApp();

    // 获取Firestore实例
    FirebaseFirestore firestore = FirebaseFirestore.instance;

    // 获取集合中的文档列表
    QuerySnapshot snapshot = await firestore.collection('your_collection').get();

    // 获取最后一个文档的ID
    String lastDocumentId = snapshot.docs.last.id;

    return lastDocumentId;
  }

  @override
  Widget build(BuildContext context) {
    return FutureBuilder<String>(
      future: getLastDocumentId(),
      builder: (BuildContext context, AsyncSnapshot<String> snapshot) {
        if (snapshot.connectionState == ConnectionState.waiting) {
          return CircularProgressIndicator();
        } else if (snapshot.hasError) {
          return Text('Error: ${snapshot.error}');
        } else {
          return Text('Last Document ID: ${snapshot.data}');
        }
      },
    );
  }
}