具有火基连接的Crud应用程序(颤振)

Question

我学习颤振。我是初学者，目前开始学习CRUD与火柴。

我是从这位伟大的绅士守则中学习的

https://github.com/mohamedHassanKa/ProductAppCourse

这是我第一次连接火力基地。我是否成功地连接了火源？我犯了这些错误。谁能教我怎么改正密码吗？

CRUDEModel.dart

import 'dart:async';
import 'package:flutter/material.dart';
import '../../locator.dart';
import '../services/api.dart';
import '../models/productModel.dart';
import 'package:cloud_firestore/cloud_firestore.dart';

class CRUDModel extends ChangeNotifier {
  Api _api = locator<Api>();

  List<Product> products;

  Future<List<Product>> fetchProducts() async {
    var result = await _api.getDataCollection();
    products = result.documents
        .map((doc) => Product.fromMap(doc.data, doc.documentID))
        .toList();
    return products;
  }

  Stream<QuerySnapshot> fetchProductsAsStream() {
    return _api.streamDataCollection();
  }

  Future<Product> getProductById(String id) async {
    var doc = await _api.getDocumentById(id);
    return  Product.fromMap(doc.data, doc.documentID) ;
  }


  Future removeProduct(String id) async{
     await _api.removeDocument(id) ;
     return ;
  }
  Future updateProduct(Product data,String id) async{
    await _api.updateDocument(data.toJson(), id) ;
    return ;
  }

  Future addProduct(Product data) async{
    var result  = await _api.addDocument(data.toJson()) ;

    return ;

  }

错误

lib/core/viewmodels/CRUDModel.dart:16:23: Error: The getter 'documents' isn't defined for the class 'QuerySnapshot<Object>'.
 - 'QuerySnapshot' is from 'package:cloud_firestore/cloud_firestore.dart' ('../../Documents/flutter_windows_3.3.4-stable/flutter/.pub-cache/hosted/pub.dartlang.org/cloud_firestore-4.1.0/lib/cloud_firestore.dart').
 - 'Object' is from 'dart:core'.
Try correcting the name to the name of an existing getter, or defining a getter or field named 'documents'.
    products = result.documents
                      ^^^^^^^^^
lib/core/viewmodels/CRUDModel.dart:28:43: Error: The getter 'documentID' isn't defined for the class 'DocumentSnapshot<Object>'.
 - 'DocumentSnapshot' is from 'package:cloud_firestore/cloud_firestore.dart' ('../../Documents/flutter_windows_3.3.4-stable/flutter/.pub-cache/hosted/pub.dartlang.org/cloud_firestore-4.1.0/lib/cloud_firestore.dart').
 - 'Object' is from 'dart:core'.
Try correcting the name to the name of an existing getter, or defining a getter or field named 'documentID'.
    return  Product.fromMap(doc.data, doc.documentID) ;
                                          ^^^^^^^^^^
lib/core/viewmodels/CRUDModel.dart:28:33: Error: The argument type 'Object Function()' can't be assigned to the parameter type 'Map<dynamic, dynamic>'.
 - 'Object' is from 'dart:core'.
 - 'Map' is from 'dart:core'.
    return  Product.fromMap(doc.data, doc.documentID) ;
                                ^
lib/core/services/api.dart:5:9: Error: Type 'Firestore' not found.
  final Firestore _db = Firestore.instance;
        ^^^^^^^^^
lib/core/services/api.dart:5:9: Error: 'Firestore' isn't a type.
  final Firestore _db = Firestore.instance;
        ^^^^^^^^^
lib/core/services/api.dart:5:25: Error: Undefined name 'Firestore'.
  final Firestore _db = Firestore.instance;
                        ^^^^^^^^^

Answer 1

既然您说您是新来的，那么您应该知道这个存储库是3年前创建的，发生了很多更新。

使用Firebase服务的新版本(确切地说是在Firestore中)，在项目中获取它的实例：

Firestore.instance // old
FirebaseFirestore.instance // new

documents属性被docs替换，因此您需要使用以下内容：

 result.documents // old - not working
 result.docs // new - will return a List<DocumentSnapshot>

要获取特定文档的Map<String, dynamic>数据，需要：

 doc.data // old
 doc.data() as Map<String, dynamic> new

要获得文档的id，您应该使用：

doc.documentId // old
doc.id // new

因此，基本上，使用新迁移的代码应该类似于以下内容：

class CRUDModel extends ChangeNotifier {
  Api _api = locator<Api>();

  List<Product> products;

  Future<List<Product>> fetchProducts() async {
    QuerySnapshot result = await _api.getDataCollection();
    products = result.docs
        .map((doc) => Product.fromMap(doc.data() as Map<String, dynamic>, doc.id))
        .toList();
    return products;
  }

  Stream<QuerySnapshot> fetchProductsAsStream() {
    return _api.streamDataCollection();
  }

  Future<Product> getProductById(String id) async {
    DocumentSnapshot doc = await _api.getDocumentById(id);
    return  Product.fromMap(doc.data() as Map<String, dynamic>, doc.id) ;
  }


  Future removeProduct(String id) async{
     await _api.removeDocument(id) ;
     return ;
  }
  Future updateProduct(Product data,String id) async{
    await _api.updateDocument(data.toJson(), id) ;
    return ;
  }

  Future addProduct(Product data) async{
    var result  = await _api.addDocument(data.toJson()) ;

    return ;

  }}

我假设这些更改是不够的，您需要使用Firebase的新术语/符号进行迁移。

我想说的是，您需要停止使用旧的存储库(无意冒犯它的所有者)，寻找一个新的项目，或者只需先看一下Firebase的正式文档。

检查一下这个：

https://firebase.flutter.dev/docs/firestore/overview

https://firebase.flutter.dev/

https://firebase.google.com/docs/flutter/setup

https://firebase.flutter.dev/docs/firestore/2.0.0_migration