more detail into models and services

services/CartService.js

@@ -0,0 +1,10 @@
+const createError = require('http-errors');
+const CartModel = require('../models/CartModel');
+const CartInstance = new CartModel();
+
+module.exports = class CartService {
+    async create(userid) {
+        const result = await CartInstance.create(userid);
+        if (!result) throw createError();
+    }
+}

services/ProductService.js

@@ -0,0 +1,25 @@
+const createError = require('http-errors');
+const ProductModel = require('../models/ProductModel');
+const ProductInstance = new ProductModel();
+
+module.exports = class ProductService {
+    async getAll() {
+        try {
+            const result = await ProductInstance.selectAll();
+            if (!result) throw createError(404, 'No products found.');
+            return result;
+        } catch(e) {
+            throw new Error(e);
+        }
+    }
+
+    async getOne(id) {
+        try {
+            const result = await ProductInstance.findOne(id);
+            if (!result) throw createError(404, 'No products found.');
+            return result;
+        } catch(e) {
+            throw new Error(e);
+        }
+    }
+}