无法读取“ID 参数”的属性

Question

这是我导入 cart.js 模型的路由器代码

var router = require('express').Router();
var Product = require('../models/products');
var Cart = require('../models/cart'); 

router.get('/add-to-cart/:_id',(req,res,next)=>{
  const productID = req.params._id;
  var cart = new Cart(req.session.cart ? req.session.cart : {});

  Product.findById(productID,(err,product)=>{
    if(err){
      res.redirect('/');
    }
    cart.add(product, product.id);
    req.session.cart = cart;
    res.redirect('/');
  })  
})

这是我的 Cart.js 代码

module.exports = function cart(oldCart){
   this.items = oldCart.items;
   this.totalQty = oldCart.totalQty;
   this.totalPrice = oldCart.totalPrice;

   this.add = function(item,id){
      var storedItem = this.items[id]; // Here is Problem
      if(!storedItem){
        storedItem = this.items[id] = {item: item, qty: 0, price: 0};
      }
      storedItem.qty++;
      storedItem.price = storedItem.item.price * storedItem.qty;
      this.totalQty++;
      this.totalPrice = storedItem.price;
   };

   this.generateArray = function(){
      var array = [];
      for (var id in this.items){
        array.push(this.items[id]);
      }
      return array;
   };
}

错误：

events.js:174 投掷者； // 未处理的“错误”事件 ^

TypeError：无法读取未定义的属性“5d9182475f539435e81a7bb9” 在 cart.add (C:\Users\Manav\Documents\Github\E_com_App\models\cart.js:7:36) 在 Product.findById (C:\Users\Manav\Documents\Github\E_com_App\routes\routes.js:85:10) 在 C:\Users\Manav\Documents\Github\E_com_App\node_modules\mongoose\lib\model.js:4589:16 在 C:\Users\Manav\Documents\Github\E_com_App\node_modules\mongoose\lib\query.js:4323:12 在 process.nextTick (C:\Users\Manav\Documents\Github\E_com_App\node_modules\mongoose\lib\query.js:2805:28) 在 process._tickCallback (internal/process/next_tick.js:61:11) 在以下位置发出“错误”事件： 在 C:\Users\Manav\Documents\Github\E_com_App\node_modules\mongoose\lib\model.js:4591:13 在 C:\Users\Manav\Documents\Github\E_com_App\node_modules\mongoose\lib\query.js:4323:12 在 process.nextTick (C:\Users\Manav\Documents\Github\E_com_App\node_modules\mongoose\lib\query.js:2805:28) 在 process._tickCallback (internal/process/next_tick.js:61:11) [nodemon] 应用程序崩溃 - 启动前等待文件更改...

查看我的完整代码：https://github.com/ma-9/E_com_NodeJS.git

Answer 1

您好，我看到了您的代码，我认为您在 Cart.js 文件和添加到购物车的路线中犯了错误。我已经解决了这个问题并向您发出拉取请求..

更新代码

module.exports = function cart(oldCart) {
this.items = oldCart.items || {};
this.totalQty = oldCart.totalQty || 0;
this.totalPrice = oldCart.totalPrice || 0;

this.add = function (item, id) {
    var storedItem = this.items[id];
    if (!storedItem) {
        storedItem = this.items[id] = { item: item, qty: 0, price: 0 };
    }
    storedItem.qty++;
    storedItem.price = storedItem.item.price * storedItem.qty;
    this.totalQty++;
    this.totalPrice = (oldCart.totalPrice || 0) + storedItem.price;
};

this.generateArray = function () {
    var array = [];
    for (var id in this.items) {
        array.push(this.items[id]);
    }
    return array;
};

当您调用 cart.add(product,product.id) 时，在您的路线中 而不是你必须调用 product._id

Answer 2

我看到你的代码，在这一行Product.findById(productID,(err,product)=>{ 你从product 模块调用findById 函数。但我只在这个文件中看到

const mongoose = require('mongoose');
const schema = mongoose.Schema;

const productSchema = new schema({
    imagePath: {type: mongoose.Schema.Types.String, required:true},
    // imagePath2: {type: mongoose.Schema.Types.String, required:true},
    // imagePath3: {type: mongoose.Schema.Types.String, required:true},
    // imagePath4: {type: mongoose.Schema.Types.String, required:true},
    // imagePath5: {type: mongoose.Schema.Types.String, required:true},
    name: {type: mongoose.Schema.Types.String, required:true},
    desc: {type: mongoose.Schema.Types.String, required:true},
    price: {type: mongoose.Schema.Types.Number, required:true},
});

module.exports = mongoose.model("DND - Products",productSchema);

您必须在本节中定义您需要的功能。例如：findById

Answer 3

mongooes db 存储具有唯一 id 的数据，键是 _id

所以编辑它

var router = require('express').Router();
var Product = require('../models/products');
var Cart = require('../models/cart'); 

router.get('/add-to-cart/:_id',(req,res,next)=>{
const productID = req.params._id;
var cart = new Cart(req.session.cart ? req.session.cart : {});

Product.findById(productID,(err,product)=>{
if(err){
  res.redirect('/');
}
cart.add(product, product._id);
req.session.cart = cart;
res.redirect('/');
})  
})