如何访问firestore文档中的集合，并将其作为列表分配给模型中的dart列表？

import 'package:cloud_firestore/cloud_firestore.dart';

final FirebaseFirestore firestore = FirebaseFirestore.instance;

Stream<QuerySnapshot> collectionStream = firestore.collection('collectionName').snapshots();

StreamBuilder<QuerySnapshot>(
  stream: collectionStream,
  builder: (BuildContext context, AsyncSnapshot<QuerySnapshot> snapshot) {
    if (snapshot.hasError) {
      return Text('Error: ${snapshot.error}');
    }

    if (snapshot.connectionState == ConnectionState.waiting) {
      return Text('Loading...');
    }

    List<DocumentSnapshot> documents = snapshot.data.docs;
    List<Model> models = documents.map((doc) => Model.fromFirestore(doc)).toList();

    return ListView.builder(
      itemCount: models.length,
      itemBuilder: (BuildContext context, int index) {
        return ListTile(
          title: Text(models[index].title),
          subtitle: Text(models[index].description),
        );
      },
    );
  },
);