尝试创建ExpansionPanelList

Question

我正在尝试建立ExpansionPanelList和即时通讯使用提供程序在那里。老实说，我无法完全理解该提供程序，但由于无法找到使之起作用的其他方式，因此我正在使用它。我已经看到提供商在其他地方使用了类似的方式，所以我认为我在这里不是完全错误的吗？

感谢您的帮助！

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

class Product {
  final String name;
  final String price;

  Product({this.name, this.price});
}

class DatabaseService {
  final CollectionReference productsCollection =
      Firestore.instance.collection('products');

  List<Product> productListFromSnapshot(QuerySnapshot snapshot) {
    // cycle through each document and create product list
    return snapshot.documents.map((doc) {
      return Product(
        name: doc.data['name'] ?? "",
        price: doc.data['price'] ?? 0,
      );
    }).toList();
  }

  Stream<List<Product>> get products {
    return productsCollection.snapshots().map(productListFromSnapshot);
  }
}

class ProductList extends StatefulWidget {
  ProductList({Key key}) : super(key: key);

  @override
  _ProductListState createState() => _ProductListState();
}

class _ProductListState extends State<ProductList> {
  @override
  Widget build(BuildContext context) {
    final products = Provider.of<List<Product>>(context) ?? [];

    return Container(
      child: ExpansionPanelList.radio(
        children: products.map<ExpansionPanel>((Product product) {
          return ExpansionPanelRadio(
            value: product.name,
            headerBuilder: (BuildContext context, bool isExpanded) {
              return ListTile(
                title: Text(product.name),
              );
            },
            body: ListTile(
              title: Text(product.name),
              subtitle: Text('some text here as subtitle text'),
              trailing: Icon(Icons.delete),
              onTap: () {
                setState(() {
                  products.removeWhere((currentItem) => product == currentItem);
                });
              },
            ),
          );
        }).toList(),
      ),
    );
  }
}


____________________





class Home extends StatelessWidget {
  final AuthService _auth = AuthService();

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      backgroundColor: Colors.blue[50],
      appBar: AppBar(
        title: Text('test'),
        backgroundColor: Colors.blue[400],
        elevation: 0.0,
        actions: <Widget>[
          FlatButton.icon(
              onPressed: () async {
                await _auth.signout();
              },
              icon: Icon(Icons.person),
              label: Text('LogOut'))
        ],
      ),
      body: HomeScreen(),
    );
  }
}


class HomeScreen extends StatefulWidget {
  HomeScreen({Key key}) : super(key: key);

  @override
  _HomeScreenState createState() => _HomeScreenState();
}

class _HomeScreenState extends State<HomeScreen> {
  @override
  Widget build(BuildContext context) {
    return Center(
      child: Column(children: <Widget>[
        RaisedButton(
            color: Colors.blue[600],
            child: Text('ProductList'),
            onPressed: () {
              Navigator.push(context,
                  MaterialPageRoute(builder: (contex) => ProductList()));
            }),
      ]),
    );
  }
}