在ListView.builder中定义从Firestore检索的文档数

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

class MyListView extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return FutureBuilder<QuerySnapshot>(
      future: FirebaseFirestore.instance.collection('your_collection').get(),
      builder: (BuildContext context, AsyncSnapshot<QuerySnapshot> snapshot) {
        if (snapshot.connectionState == ConnectionState.waiting) {
          return CircularProgressIndicator();
        }
        if (snapshot.hasError) {
          return Text('Error: ${snapshot.error}');
        }
        final int documentCount = snapshot.data.docs.length;
        return ListView.builder(
          itemCount: documentCount,
          itemBuilder: (BuildContext context, int index) {
            final DocumentSnapshot document = snapshot.data.docs[index];
            // 构建列表项
            return ListTile(
              title: Text(document['title']),
              subtitle: Text(document['subtitle']),
            );
          },
        );
      },
    );
  }
}