I was trying to use map but there is no way for me to take the data from the models/cart.js to my controllers/cart.js, basically I need an alternative to be able to enter the data inside my req.body.products through object notation (products is an array).

[models/cart.js]

const fs = require("fs").promises;
const { customAlphabet } = require("nanoid");
const nanoid = customAlphabet("1234567890", 5);

class Cart {
  constructor(txtNameFile) {
    this.txtNameFile = txtNameFile;
    this.dataCart = [];
  }

  async fileInJSON() {
    let fileTxt = await fs.readFile(this.txtNameFile, "utf-8");
    let type = JSON.parse(fileTxt);
    return type;
  }

  async fileSaving(item) {
    let type = JSON.stringify(item);
    await fs.writeFile(this.txtNameFile, type);
  }

  async createCart(data) {
    try {
      const cart = await this.fileInJSON();
      const newCart = {
        id: Number(nanoid()),
        date: new Date().toLocaleString(),
        products: [
          {
            id: Number(nanoid()),
            title: data.products[0].title,
            price: Number(data.products[0].price),
            image: data.products[0].image,
            description: data.products[0].description,
            stock: data.products[0].stock,
            date: new Date().toLocaleString(),
            code: data.products[0].code,
          },
        ],
      };
      cart.push(newCart);
      await this.fileSaving(cart);

      return newCart;
    } catch (error) {
      console.log(error);
    }
  }

  async deleteCart(id) {
    try {
      const cart = await this.fileInJSON();
      const newCart = cart.filter((cart) => cart.id !== Number(id));
      await this.fileSaving(newCart);
      return newCart;
    } catch (error) {
      console.log(error);
    }
  }

  async getProductsInCart(id) {
    try {
      const cart = await this.fileInJSON();
      const productos = cart.find((cart) => cart.id === Number(id));
      return productos;
    } catch (error) {
      console.log(error);
    }
  }

  // GET in endpoint  /:id/products

  // POST in endpoint  /:id/products
  async addProduct(id, data) {
    try {
      const cart = await this.fileInJSON();
      const newCart = cart.map((cart) => {
        if (cart.id === Number(id)) {
          cart.products.push({
            id: data.id,
            title: data.title,
            price: Number(data.price),
            image: data.image,
            description: data.description,
            stock: data.stock,
            date: new Date().toLocaleString(),
            code: data.code,
          });
        }
        return cart;
      });
      await this.fileSaving(newCart);
      return newCart;
    } catch (error) {
      console.log(error);
    }
  }

  // DELETE in endpoint  /:id/products/:id_prod

  async deleteEntireProduct(id, id_prod) {
    try {
      const cart = await this.fileInJSON();
      const newCart = cart.map((cart) => {
        if (cart.id === Number(id)) {
          cart.products = cart.products.filter(
            (product) => product.id !== Number(id_prod)
          );
        }
        return cart;
      });
      await this.fileSaving(newCart);
      return newCart;
    } catch (error) {
      console.log(error);
    }
  }

  // try {
  //   const cart = await this.fileInJSON();
  //   const newCart = {
  //     id: Number(nanoid()),
  //     timeStamp: new Date().toLocaleString(),
  //     products: data.products,
  //   };

  //   cart.items.push(newCart);
  //   await this.fileSaving(cart);
  //   return newCart;
  // } catch (error) {
  //   console.log(error);
  // }
}
module.exports = Cart;

[controllers/cart.js]

const Cart = require("../models/cart");
const carrito = new Cart("cart.json");
const { customAlphabet } = require("nanoid");
const nanoid = customAlphabet("1234567890", 5);

const creatingCartsWithProducts = async (req, res) => {
  const newCart = await carrito.createCart(req.body);
  return res.json(newCart);
};

const listOfProducts = async (req, res) => {
  const carts = carrito.getProductsInCart(req.params.id);
  return res.json(await carts);
};

module.exports = {
  creatingCartsWithProducts,
  listOfProducts,
};

[routes/cart.js]

const express = require("express");
const router = express.Router();
const { creatingCartsWithProducts, listOfProducts } = require("../controllers/cart");

router.post("/", creatingCartsWithProducts);
router.get("/:id/productos", listOfProducts);

module.exports = router;

[cart.json]

[
  {
    "id": 63589,
    "date": "6/2/2022, 7:04:05 PM",
    "products": [
      {
        "title": "Producto NsiiiiiiIKE TIKETIT",
        "price": 5500,
        "image": "https://www.google.com/url?sa=i&url=https%3A%2F%2Fwww.pinterest.com%2Fpin%2F569098989827098984%2F&psig=AOvVaw2X_Z_7Z_X_Z_X_X_Z_X_&ust=1548790984533000&source=images&cd=vfe&ved=0CAIQjRxqFwoTCKDqx-_3-4CFQAAAAAdAAAAABAD",
        "description": "Descripcion del producto 3",
        "stock": 20,
        "date": "6/2/2022, 7:04:05 PM",
        "code": "5ABBE5"
      }
    ]
  }
]