如何从firestore获取数据并将其设置为Flutter TextFormField

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

class MyForm extends StatefulWidget {
  @override
  _MyFormState createState() => _MyFormState();
}

class _MyFormState extends State<MyForm> {
  String data = '';

  @override
  void initState() {
    super.initState();
    fetchData();
  }

  Future<void> fetchData() async {
    // 获取Firestore实例
    FirebaseFirestore firestore = FirebaseFirestore.instance;

    // 获取数据
    DocumentSnapshot snapshot = await firestore.collection('your_collection').doc('your_document').get();

    // 将数据设置到TextFormField
    setState(() {
      data = snapshot.data()['your_field'];
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('My Form'),
      ),
      body: Center(
        child: TextFormField(
          initialValue: data,
          decoration: InputDecoration(
            labelText: 'Your Data',
          ),
        ),
      ),
    );
  }
}