Express Routes and Controller (Thapa)

#1: Introduction to Build REST API with Node, Express, Mongo & Mongoose in Hindi

Features we will learn in This ✅

Rest API #2: Lets create Server with Express JS

Go to project directory
npm init -y
echo>app.js

Rest API #2: Lets create Server with Express JS

Basic Express Setup and using `dotenv` & `mongoose`

Define environment variables in a .env file:

# .env
PORT=5000
MONGODB_URL=mongodb://localhost:27017/myDatabase

Loading Environment Variables in App.js Using dotenv

// Import dotenv
const dotenv = require("dotenv");
 
// Load environment variables
dotenv.config();
 
const MONGODB_URL = process.env.MONGODB_URL; // MongoDB URL
const PORT = process.env.PORT || 3000;      // Server port

Connecting MongoDB using Mongoose using MONGODB_URL:

// Import mongoose
const mongoose = require("mongoose");
 
// Connect to MongoDB
mongoose
    .connect(MONGODB_URL, { useNewUrlParser: true, useUnifiedTopology: true })
    .then(() => console.log("Connected to MongoDB"))
    .catch((err) => console.error("MongoDB connection error:", err));

Running Express Server on the specified PORT:

// Import express
const express = require("express");
 
const app = express(); // Initialize Express
 
// Express Logic .........
 
// Start the server
app.listen(PORT, () => {
    console.log(`Server is running on http://localhost:${PORT}`);
});

Notes:

**Use .env for sensitive data like PORT and MONGODB_URL.
Error Handling: Always handle MongoDB connection errors.
Middleware: Add any required middleware (e.g., express.json()).
Keep .env Secure: Add .env to .gitignore.

Rest API #3: Setup Routes & Controllers using Express Routers in Hindi

Routes and Controller

We generally made Routes simply with app.get()

// app.js
 
app.get("/", (req, res) =>{
	res.send("Hi, I am live");
});

But in Future if we gonna make our application big, using app.get() for each routes will not be efficient

So we use Routes and Controller

Routes -> Tells what to do
Controller -> Then it do

Added Routes/products.js and controller/products.js

server
├── controllers
|       └── products.js   
├── routes
|       └── products.js  
└── app.js

Setup Controller controllers/products.js : Define the Function to be used for each Routes

const getAllProducts = async (req, res)=>{
	res.status(200).json(msg: "I am getAllProducts"});
}
 
const getAllProductsTesting = async (req, res)=>{
	res.status(200).json(msg: "I am getAllProductsTesting"});
}
 
module.exports = {getAllProducts, getAllProductsTesting};

Setup Router routes/proudcts.js: Define the routes and Use the Functions in each routes

const router = express.Router(); // import router
const {getAllProducts, getAllProductsTesting} = require("../controllers/products"); // import controller
 
// Route for All products through `getAllProducts()` Function
router.route("/").get(getAllProducts);
// routes for getAllProducts for testing purpose
router.route("/testing").get(getAllProductsTesting);
 
module.exports = router;

Setup Server (app.js):

// import Router
const productsRoutes = require("./routes/products"); 
 
// Home Page
app.get("/", (req, res) => {
    res.send("Hi, I am live"); // localhost:5000/
});
 
// Middleware to use Router
app.use("/api/products", productsRoutes);
// Routes:
// - localhost:5000/api/products/ -> getAllProducts
// - localhost:5000/api/products/testing -> getAllProductsTesting

Rest API #5: Introduction to MongoDB & Mongoose || Connect Backend to Database

mongoose Connection function

mongoose.connect(uri, options, callback)

Added db/connect.js

server
├── controllers
|       └── products.js 
├── db
|       └── connect.js  
├── routes
|       └── products.js  
└── app.js

Connect MonogoDB using its framework mongoose in dp/connect.js using mongoose

// import mongoose
connect mongoose = require("mongoose");
 
uri = "mongodb+srv://thapa:myPassword@thapaapi.mi9m8rx.mongodb.net/ThapaAPI?retryWrites=true&w=majority"; // replace with the uri of your database
 
const connectDB = ()=>{
	console.log("connect db");
	return mongoose.connect( uri, {   
		// option
		useNewUrlParser: true,
		useUnifiedTopology: true,
	});
};
 
module.exports = connectDB;

Import db/connect.js and use connectDB() in App.js

...
// import connectDB
const connectDB = require("./db/connect.js");
 
// Express Logic.....
 
const start = async() => {
	try{
		await connectDB(); // this connect will return promise
		app.listen(PORT, () => {
			console.log(`${PORT} Yes I am connected`);
		});
	} catch (error) {
		console.log(error),
	}
}

Note:

async and await are used to handle asynchronous operations in JavaScript in a simpler, more readable way compared to traditional approaches like callbacks or .then() chaining with Promises.
async Declares a function that always returns a Promise.
await Pauses the execution of the async function until the Promise is resolved or rejected. ( Can only be used inside an async function.)

await connectDB: await ensure that the applications only starts listening on the specified port (via app.listen()) after successfully establishng a connection to the database

Promises : A Promise is an object in JavaScript used to handle asynchronous operations. It represents a value that may be available now, in the future, or never. It allows you to work with asynchronous code in a clean, manageable way without deeply nested callbacks (callback hell).**

States of a Promises: Pending, Fulfilled and Rejected
Immutable: Once a Promise is fulfilled or rejected, its state cannot change.

Rest API #7: Create Schema & Model (Collection & Tables) using Mongoose & Express JS

Let Our data is like this

{
	"Proudcts":[
		{ 
			"_id" : "9834dsgfw83yrhsf",
			"name" : "iphone",
			"price" : 154,
			"featured" : false,
			"rating" : 4.8,
			"createdAt" : "2022-11-17T11:39:09.640Z",
			"company" : "apple",
			"__v" : 0
		},
		{
			"_id" : "9834dsgfw83djfdkf",
			"name" : "redmi note 9 pro",
			"price" : 115,
			"featured" : false,
			"rating" : 3.5,
			"createdAt" : "2022-11-17T11:39:09.640Z",
			"company" : "xiaomi",
			"__v" : 0
		},
		...
	
	]
}

Now We need to define the Schema on models

Added models/products.js

server
├── controllers
|       └── products.js 
├── db
|       └── connect.js  
├── models
|       └── products.js  
├── routes
|       └── products.js  
└── app.js

Setup Model models/proudcts.js: Define the Schemas or of the Document(Table)

// import mongoose
const mongoose = require("mongoose");
 
// Make Schema using mongoose `schema()` function
const productSchema = new mongoose.Schema({
 /* Copy past one Sample Document
 		{ 
			"_id" : "9834dsgfw83yrhsf",
			"name" : "iphone",
			"price" : 154,
			"featured" : false,
			"rating" : 4.8,
			"createdAt" : "2022-11-17T11:39:09.640Z",
			"company" : "apple",
			"__v" : 0
		}
 */
})
 
// Export the model. 
module.exports = mongoose.model("Product", productSchema)

Update :

Remove "" from field key to make JSON format to Object
Remove _id & __v , it will be automatically assigned
Write Attribute or Properties of the field in place of sample value

const mongoose = require("mongoose");
 
const productSchema = new mongoose.Schema({
			name : {
				type: String,
				required: true, // must be mandatory to enter
			},
			price : {
				type: Number,
				required: [true, "price must be provide"], // mandatory to enter, and error message if not entered
			},
			featured : {
				type: Boolean,
				default: false, // default value
			},
			rating : {
				type: Number,
				default: 5.0,
				},
			createdAt : {
				type: Date,
				default: Date.now(), // Current Date
			},
			company : {
				type: String,
				enum: {
					values: ["apple", "samsung", "dell", "mi"], // only companies out of this list are allowed in our API
					message: `{value} is not supported` // error message if some other value is tried to assign
					},
			},
});
 
module.exports = mongoose.model("Product", productSchema)

Note:

All attributes of each field are in lowercase type, required, default, enum, message, values in mongoose
All attributes values are in Capitalize form String, Number, Boolean, Date in mongoose
Export model name should be singular Procuct in mongoose model function, it will automatic pluralize to Products in mongoDB Database

Rest API #8: Stored API data (JSON) in Database using Express & Mongoose

Stored Rest API data (.json) to mongoDB

Added productDB.js & products.json

server
├── controllers
|       └── products.js 
├── db
|       └── connect.js  
├── models
|       └── products.js  
├── routes
|       └── products.js  
├── app.js
├── productDB.js
└── products.json

Let our Data is stored in prodcuts.json

[
	{
		"name" : "iphone",
		"price" : 154,
		"featured" : false,
		"company" : "apple",
	},
	{
		"name" : "redmi note 9 pro",
		"price" : 115,
		"company" : "xiaomi",
	},
	...
]

Values that are not present for a product, like rating, Date is Autofill by our model/product.js if set default

Setup productDB.js

require("dotenv").config();
const connectDB = require("./db/connect"); // import `connect.js`
const Product = require("/models/product"); // import `models/product.js`
 
// Get data from JSON
const ProductJson = ("./products.json") // Default and Implictly exported
 
// Below statement was Written inside `App.js` but for simplicty and Indepent, we write here for now : )
const start = async() => {
	try{
		await connectDB(process.env.MONGODB_URL); // connect to database
		console.log("success");
		await Product.create(ProductJSON)
	} catch (error) {
		console.log(error),
	}
};
 
start();

For this Video run the Product.js Independently

node productDB.js

Hurray , Data is stored in MongoDB with Collection name products plural automatically

Express Routes and Controller (Thapa)

#1: Introduction to Build REST API with Node, Express, Mongo & Mongoose in Hindi

Rest API #2: Lets create Server with Express JS

Rest API #2: Lets create Server with Express JS

Basic Express Setup and using dotenv & mongoose

Rest API #3: Setup Routes & Controllers using Express Routers in Hindi

Routes and Controller

Rest API #5: Introduction to MongoDB & Mongoose || Connect Backend to Database

Rest API #7: Create Schema & Model (Collection & Tables) using Mongoose & Express JS

Rest API #8: Stored API data (JSON) in Database using Express & Mongoose

Basic Express Setup and using `dotenv` & `mongoose`