node.js - 尝试将项目添加到购物车时,项目数组为空
问题描述
服务器所以我试图将项目添加到购物车但数组是空的,我找不到问题。我认为 node.js 的后端工作正常,因为当我通过在浏览器中键入 URL http://localhost:4000/cart/5dd7668f33c21d811b74f403将商品添加到购物车时,它会增加购物车数量并重定向到http:// /localhost:4000/cart/但是当我导航到http://localhost:3000/cart/时,浏览器中没有显示任何内容,并且当我使用 chrome 开发人员工具检查它时,项目数组是空的。我认为前端会做出反应并且后端未正确链接。我添加了它的图片以进一步澄清,这是我的应用程序的代码。服务器.js
const express = require("express");
const app = express();
const bodyParser = require("body-parser");
const cors = require("cors");
const cookieParser = require("cookie-parser");
const mongoose = require("mongoose");
let Book = require("./models/bookModel");
var session = require("express-session");
var MongoStore = require("connect-mongo")(session);
var flash = require("connect-flash");
const port = 4000;
app.use(cors());
app.use(bodyParser.json());
app.use(cookieParser());
app.use(
session({
secret: "keyboard cat",
resave: false,
saveUninitialized: true,
store: new MongoStore({ mongooseConnection: mongoose.connection }),
cookie: { maxAge: 180 * 60 * 1000 }
})
);
app.use(flash());
mongoose.connect("mongodb://127.0.0.1:27017/books", { useNewUrlParser: true });
const connection = mongoose.connection;
connection.once("open", function() {
console.log("MongoDB database connection established successfully..");
});
const bookRoutes = express.Router();
app.use("/books", bookRoutes);
const cartRoutes = express.Router();
app.use("/cart", cartRoutes);
bookRoutes.route("/").get(function(req, res) {
Book.find(function(err, books) {
if (err) {
console.log(err);
} else {
res.json(books);
}
});
});
bookRoutes.route("/:id").get(function(req, res) {
let id = req.params.id;
Book.findById(id, function(err, book) {
res.json(book);
});
});
cartRoutes.route("/").get(function(req, res) {
var cart = req.session.cart;
var displayCart = { items: [], total: 0 };
var total = 0;
for (var item in cart) {
displayCart.items.push(cart[item]);
total += cart[item].qty * cart[item].price;
}
displayCart.total = total;
return res.json(displayCart);
});
cartRoutes.route("/:id").get(function(req, res) {
req.session.cart = req.session.cart || {};
var cart = req.session.cart;
let id = req.params.id;
Book.findById(id, function(err, book) {
if (err) {
console.log(err);
}
if (cart[id]) {
cart[id].qty++;
} else {
cart[id] = {
item: book._id,
title: book.title,
price: book.price,
qty: 1
};
}
console.log(req.session.cart);
res.redirect("/cart");
});
});
app.listen(port, function() {
console.log("Server is running on Port: " + port);
});
应用程序.js
import React, { Component } from "react";
import { BrowserRouter as Router, Route, Link } from "react-router-dom";
import BooksList from "./components/book-list.component.js";
import BookDetails from "./components/book-details.component.js";
import "bootstrap/dist/css/bootstrap.min.css";
import Navigation from "./components/navigation.component";
import Cart from "./components/cart1.component";
class App extends Component {
render() {
return (
<Router>
<Navigation></Navigation>
<Route
path="/"
exact
render={() => (
<div className="container">
<BooksList></BooksList>
</div>
)}
></Route>
<Route path="/books/:id" exact component={BookDetails}></Route>
<Route path="/cart" exact component={Cart}></Route>
</Router>
);
}
}
export default App;
book-details.componentjs
import React, { Component } from "react";
import "../css/styles.css";
import axios from "axios";
export default class BookDetails extends Component {
constructor(props) {
super(props);
this.state = {
book: [],
items: []
};
}
componentDidMount() {
axios
.get("http://localhost:4000/books/" + this.props.match.params.id)
.then(response => {
this.setState({ book: response.data });
})
.catch(function(err) {
console.log(err);
});
}
AddToCart = e => {
let id = e.currentTarget.getAttribute("id");
axios.get(`http://localhost:4000/cart/${id}`).then(() => {
window.location.href = "http://localhost:3000/cart";
});
};
render() {
const { book, quantity } = this.state;
return (
<div className="container">
<div className="row">
<div className="col sm-4">
<img src={`./images/${book.cover}`}></img>
</div>
<div className="col sm-8">
<h2>{book.title}</h2>
<ul>
<li>Category: {book.category}</li>
<li>Author: {book.author}</li>
</ul>
<p className="button blue">${book.price}</p>
<p>{book.description}</p>
<button id={book._id} onClick={this.AddToCart}>
Add to Cart
</button>
</div>
</div>
</div>
);
}
}
cart1.component.js
import React, { Component } from "react";
import axios from "axios";
import CartItem from "./cart1-item.component.js";
import "bootstrap/dist/css/bootstrap.min.css";
import { throws } from "assert";
export default class Cart extends Component {
constructor(props) {
super(props);
this.state = {
items: []
};
}
componentDidMount() {
axios
.get("http://localhost:4000/cart/")
.then(response => {
this.setState({
items: response.data.items
});
})
.catch(function(err) {
console.log(err);
});
}
checkItems() {
return this.state.items.map((currItem, i) => {
return <CartItem book={currItem} key={i}></CartItem>;
});
}
Calculate = item => {
return item.qty * item.price;
};
render() {
return (
<div className="container">
<div className="row">{this.checkItems()}</div>
</div>
);
}
}
购物车-tem1.component.js
import React, { Component } from "react";
import "bootstrap/dist/css/bootstrap.min.css";
const CartItem = props => {
return (
<div className="container">
<h2>{props.book.title}</h2>
</div>
);
};
export default CartItem;
我已经坚持了将近一个星期,并尽我所能使其工作,但无济于事,任何帮助将不胜感激
[chromedevelopertools ][2]
解决方案
不尝试就很难调试所有内容,但我很确定您的会话有问题。
会话由 cookie(浏览器在每个请求上发送的东西)实现,出于安全原因,它们依赖于域。它们不能很好地与单页应用程序配合使用。
当您转到端口:4000 时,浏览器会为您发送 cookie,但在端口:3000 上,axios 应该从其他域发送 cookie。尝试在您的通话中添加此配置:
axios.get('xxx', {withCredentials: true});
它~可能会起作用,尽管我觉得你需要在其他地方做一些额外的工作才能首先初始化那个 cookie。
如果您要使用 SPA(这是当今流行的选择),我建议您不要使用会话并尝试使您的服务器“无状态”。它还会有其他好处。你需要实现像 Oauth 或 JWT 之类的东西,而不是那个 cookie(如果你刚开始的话,我推荐 Jwt)。那有足够的关键字供您搜索!:)
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