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node version: v13.14.0 and npm version:6.14.4

I tried to run this code with the latest as well as the previous builds of node but it didn't work out.

This is what I got after running npm start:

$ npm start

> 1st-app@1.0.0 start D:\web development\node\1st app
> nodemon app.js

[nodemon] 2.0.7
[nodemon] to restart at any time, enter `rs`
[nodemon] watching path(s): *.*
[nodemon] watching extensions: js,mjs,json
[nodemon] starting `node app.js`
internal/validators.js:121
    throw new ERR_INVALID_ARG_TYPE(name, 'string', value);
    ^

TypeError [ERR_INVALID_ARG_TYPE]: The "path" argument must be of type string. Received undefined
    at validateString (internal/validators.js:121:11)
    at Object.dirname (path.js:583:5)
    at Object.<anonymous> (D:\web development\node\1st app\models\cart.js:5:10)
    at Module._compile (internal/modules/cjs/loader.js:1118:30)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:1138:10)
    at Module.load (internal/modules/cjs/loader.js:982:32)
    at Function.Module._load (internal/modules/cjs/loader.js:875:14)
    at Module.require (internal/modules/cjs/loader.js:1022:19)
    at require (internal/modules/cjs/helpers.js:72:18)
    at Object.<anonymous> (D:\web development\node\1st app\controllers\shop.js:2:14) {
  code: 'ERR_INVALID_ARG_TYPE'
}
[nodemon] app crashed - waiting for file changes before starting...

Here is my cart.js code:

const fs = require("fs");
const path = require("path");

const p = path.join(
    path.dirname(process.mainModule.fileName),
    "data",
    "cart.json"
);

module.exports = class cart {
    static addProduct(id, productPrice) {
        //Fetch the previous cart
        fs.readFile(p, (err, fileContent) => {
            let cart = { products: [], totalPrice: 0 };
            if (!err) {
                cart = JSON.parse(fileContent);
            }
            //Analyse the cart => Find existing product
            const existingProductIndex = cart.products.findIndex(
                (prod) => prod.id === id
            );
            const existingProduct = cart.products[existingProductIndex];
            let updatedProduct;

            // Add new product/ increase quantity
            if (existingProduct) {
                updatedProduct = {...existingProduct };
                updatedProduct.qty = updatedProduct.qty + 1;
                cart.products = [...cart.products];
                cart.products[existingProductIndex] = updatedProduct;
            } else {
                updatedProduct = { id: id, qty: 1 };
                cart.products = [...cart.products, updatedProduct];
            }
            cart.totalPrice = cart.totalPrice + +productPrice;
            fs.writeFile(p, JSON.stringify(cart), (err) => {
                console.log(err);
            });
        });
    }
};

This is my shop.js code:

const Product = require("../models/product");
const Cart = require("../models/cart");

exports.getCart = (req, res, next) => {
    res.render("shop/cart", {
        pageTitle: "Your Cart",
        path: "/cart",
    });
};

exports.postCart = (req, res, next) => {
    const prodId = req.body.productId;
    Product.findById(prodId, (product) => {
        Cart.addProduct(prodId, product.price);
    });
    res.redirect("/cart");
};

I tried everything which I could but this error is not resolved and I am stuck here.

Any help will be great.

Thank You in advance.

Khetesh Singh
  • 11
  • 1
  • This suggests the “n” in fileName should be lowercase (hence the error about path receiving undefined): https://stackoverflow.com/a/18620495/4722345 – JBallin May 13 '21 at 05:52
  • In addition to the typo pointed out by @JBallin, process.mainModule is deprecated as of v14.0.0. Also be aware that if you run this app through another app, such as pm2, forever or mocha, this will not work. Given this is being launched by nodemon, THIS is what could be causing the issue. – Will Walsh May 13 '21 at 05:56
  • Thank you so much...the error is resolved by changing it to "n". – Khetesh Singh May 13 '21 at 08:10

0 Answers0