BackEnd (NodeJs ExpressJs EJS MongoDB)

🙏🏻Welcome to our Repository. In this repo, you will learn A to Z about Backend.

Steps to setup a backend for any project.

Express JS Setup

Use the npm init command to create a package.json file for your application
```
npm init 
```
Now install Express
```
npm install express
```

Hello World Code in `app.js` file

Visit to npmjs.com or expressjs.com and Copy the boiler plate (hello world) code

const express = require('express')
const app = express()
const port = 3000

app.get('/', (req, res) => {
    res.send('Hello World!')
})

app.listen(port, () => {
    console.log(`App listening on port ${port}`)
})

EJS setup

Install EJS
```
npm install ejs
```

Set view engine

app.set("view engine", "ejs")

Now your code look like this

const express = require('express') 
const app = express()
const port = 3000

app.set("view engine", "ejs")  

app.get('/', (req, res) => {
    res.send('Hello World!')
})

app.listen(port, () => {
    console.log(`App listening on port ${port}`)
})

Create views Folder

Create ejs files inside views folder

Example - index.ejs

Inside index.ejs, Paste normal html boilder plate code

<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Index.Js File</title>
</head>

<body>
    <h1>Welcome to Index.Js file (Home Route)</h1>
</body>

</html>

Render `index.ejs` file inside route

app.get('/', (req, res) => {
    res.render('index')
})

Now your code (app.js) look like this.

const express = require('express') 
const app = express()
const port = 3000

app.set("view engine", "ejs") 

app.get('/', (req, res) => {
    res.render('index')
})

app.listen(port, () => {
    console.log(`App listening on port ${port}`)
})

Start the Server

Run this command

node app.js

But, there is a problem in this way. Whenever you made some changes in your file, you have to restart the server again and again to reflect the changes.

So the better approach is to start the server using nodemon

Install Nodemon

npm install nodemon

Now to start server, Just type the command given below

nodemon app.js

Express static files setup

Create public Folder
Create images, stylesheets and javascripts folder inside public folder.
You can create files inside these folders. For e.g. style.css in stylesheets folder.

Now write this in app.js file to serve static files

app.use(express.static('./public'))

Now your code (app.js) look like this

const express = require('express') 
const app = express()
const port = 3000

app.set("view engine", "ejs") 
app.use(express.static('./public'))

app.get('/', (req, res) => {
    res.render('index')
})

app.listen(port, () => {
    console.log(`App listening on port ${port}`)
})

Adding Stylesheet

<link rel="stylesheet" href="/stylesheets/style.css">

Now your index.ejs file looks like

<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Index.Js File</title>

    <!-- Linking stylesheet -->
    <link rel="stylesheet" href="/stylesheets/style.css">
    
</head>

<body>
    <h1>Welcome to Index.Js file (Home Route)</h1>
</body>

</html>

And your directory/folder structure looks like this

.
├── app.js
├── package.json
├── public
│   ├── images
│   ├── javascripts
│   └── stylesheets
│       └── style.css
└── views
    ├── index.ejs

EXPRESS GENERATOR

You can easily do all the above task by just using express generator and save your time to setting up backend again and again.

Install the application generator as a global npm package

npm install -g express-generator

Steps to setup

Open cmd/terminal and type the command below to create an app.

express --view=ejs yourAppName

Now change directory:

cd yourAppName

Install dependencies:

npm install

Now open it on vs code

code .

Your app is created and opened in VS code.

Run your app by using this command

npx nodemon

Note : directory/folder generated by express generator, structure looks like this

.
├── app.js
├── bin
│   └── www
├── package.json
├── public
│   ├── images
│   ├── javascripts
│   └── stylesheets
│       └── style.css
├── routes
│   ├── index.js
│   └── users.js
└── views
    ├── error.ejs
    ├── index.ejs
    └── layout.ejs

Some changes that you have to keep in your mind.

Previously we write app.get, but now you have to write router.get
Previously we start our server using npm/npx nodemon yourFileName, but now we have to write npx nodemon only.

Linking css or other files method remain same.

<link rel="stylesheet" href="/stylesheets/style.css">

MongoDB

MongoDB is Non-Relational Database.

Here is the table that represent -> If you code then what happen in mongodb

Code Side		MongoDB Side Action Here
DB Setup	⟶	DB Formation
Model	⟶	Collection
Schema	⟶	Documents

Database Setup == DB Formation

All the data of an app == Database
And its setup in code side is called DB Setup and in MongoDb side it is called DB formation.

Model == Collection

Suppose Amazon have a data base and amazon data base is divided into four parts.

User DB
Sales DB
Admin DB
Profit DB

These parts are called MODELS in code side and COLLECTION in MongoDB side.

Schema == Documents

Lets suppose UserDB have users and user must have their name, address and phone no.

These are called Schema (in code side) and Documents (in mongo db side)

In simple work, how each documents of user look like is called schema

Lets set up Data Base

Now we are going to setup a database. To do so, we have to follow these steps.

Install MongoDB Community Edition just like any other application
Install Mongoose Js
```
npm install mongoose
```

Require and Setup connection for database

const mongoose = require("mongoose")

// Connect to local host mongodb server 
mongoose.connect("mongodb://127.0.0.1:27017/amazonDB")
// The above line create a database in mongodb named "amazonDB"

Make Schema (Document)

const userSchema = mongoose.Schema({
    username: String,
    name: String,
    age: Number
})

Create Model (collection) and Export

module.exports = mongoose.model("userDB", userSchema)

So what we did?

We created a Database names amazonDB, means Data Setup in code side and DB formation in MongoDB side.
We created a model (in code side) or collection (in mongodb side) named userDB.
We created a document that contains data format about user, means Schema created in code side named userSchema and document created in mongodb side.

DATABASE Structure

── amazonDB
        └── userDB
                └── userSchema

Now lets do operations in db

write this code in user.js file

const mongoose = require("mongoose")

// Connect to local host mongodb server 
mongoose.connect("mongodb://127.0.0.1:27017/amazonDB")
// The above line create a database in mongodb named "amazonDB"

const userSchema = mongoose.Schema({
  username: String,
  name: String,
  age: Number
})

module.exports = mongoose.model("userDB", userSchema)

And in index.js to create db

var express = require('express');
var router = express.Router();

// Importing mongodb setup code that is written in user.js
const userModel = require("./users")

/* GET home page. */
router.get('/', function(req, res, next) {
  res.render('index');
});

// Creating model. 
router.get("/create", async function (req, res){
  const createdUser = await userModel.create({
    // these are schema details
    username: "aman",
    name: "aman kumar sinha",
    age: 20
  });
  res.send(createdUser);
})
// Note: all the things related to userModel is asynchronous nodejs function. So always write async and await

module.exports = router;

When you visit http://localhost:3000/create your data base will be created.

To see the database is created or not. Open terminal. Type command

mongod

This will open your mongodb server. Then open a one more tab or a new terminal and type command.

mongosh

And after that in same terminal type these commands one by one

// This command show all the db in your computer
show dbs

// Now go to the db that you have created. In our case, its amazonDB
use amazonDB

// Now write this command to see all the collection inside amazon db
show collections

// Now type this to see what is in userdb collection
db.userdbs.find()

// Your userdb's user data look like this
[
  {
    _id: ObjectId("65411c6ea1039336d4d364cc"),
    username: 'aman',
    name: 'aman kumar sinha',
    age: 20,
    __v: 0
  }
]

To read data using nodejs code (add this line in index.js)

// See data (READ data)
router.get("/allUser", async function(req, res){
  let users = await userModel.find()
  res.send(users)
})

Go to localhost:3000/allUser to read data

Note: .find() return you all the use. .findOne() return you one user.

router.get("/allUser", async function(req, res){
  let users = await userModel.findOne({username:"aman"})
  res.send(users)
})

Delete Data code

// DELETE Data
router.get("/delete", async function(req, res){
  let deletedUser = await userModel.findOneAndDelete({
    username:"aman"
  })
  res.send(deletedUser)
})
// the above code will find user that username is aman and delete it and return its data to deletedUser variable

Session and cookies:

Data that saved on client side is called cookies and the data that saved on server is called session.

To use session, you need to install a package form npm

npm install express-session

In app.js write some lines to use express-session

const session = require('express-session');

app.use(session({
  secret: 'your-secret-key-here', // A secret key to sign the session ID cookie
  resave: false, // means if data is not modified, don't resave.
  saveUninitialized: false // means don't save uninitailized data
}));

now you can make/create session (open index.js file)

// In any route you can set session.
// in our session session is set in home route and if someone visit our home route, session will create and if you open checkSession route, you can see session.

router.get('/', function(req, res, next) {

    // Session code here
    req.session.anyExampleNameHere = 'exampleUserData'; // Storing user data in the session

    res.render('index');
});

// READ Session
router.get('/checkSession', function(req, res){

    if(req.session.anyExampleNameHere == "exampleUserData"){
        console.log(req.session)
        res.send("Session saved. see on your console/terminal")
    }
    else{
        res.send("Session data is not available or deleted")
    }
    
})

To delete session, code is here

// Deleting/Destroy session
router.get("/removeSession", function(req, res){
  req.session.destroy(function(err){
    if(err) throw err;
    res.send("session deleted")
  })
})

Cookies-Parser

Cookies are already setup in your code by exress generetor, still I am proving the code

var cookieParser = require('cookie-parser');

app.use(cookieParser());

Create and read cookie code (index.js)

router.get('/', function(req, res, next) {

  // Cookies code here
  res.cookie("nameHere", "valueHere")

  res.render('index');
});

// Read cookie

router.get('/checkCookie', function(req, res){
  console.log(req.cookies)
  res.send("check console/terminal for cookie")
})

// Delete cookie

router.get('/deleteCookie', function(req, res){
  res.clearCookie("nameHere")
  res.send("cleared cookie")
})

Checkout Our More Branches

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Authentication and Authorization
Projects
And More

Code to see branches

git branch

checkout to that branch code

git checkout <branch-name>

Thank YOU

Beginner-Friendly Projects with EJS, Node.js, Express.js & MongoDB

Explore these beginner-friendly projects, featuring authentication and authorization functionalities, built using EJS, Node.js, Express.js, and MongoDB.

Projects:

Blog Post Project
- Features:
  - User Authentication: Implement user registration and login seamlessly.
  - Post Management: Create, edit, and delete posts effortlessly.
  - User-Centric Viewing: Browse through all posts authored by a specific user.
  - Profile Enhancement: Upload and update profile images with ease.
  - Engagement Features: Like and unlike posts to interact with content dynamically.
- GitHub Repository Link
To Do App
- GitHub Repository Link
- Live Demo

Feel free to explore and contribute to these projects!

AmanKumarSinhaGitHub/Backend-Node-Express-EJS-MongoDB