How to connect Express js with MongoDB

Prerequisite tutorial:

Install MongoDB in on Ubuntu 18.04

How To Install MongoDB Compass

1. Install Nodejs:

Node.js

version check:
node -v

2. Install express.js, mongoose, morgan and nodemon

mkdir blog_expressjs
cd blog_expressjs
npm init -y  //Initialise and Configure Our Project
npm i express mongoose morgan dotenv cors --save
                       // express install
                       // mongoose: mongodb install
                       // morgan: for show log
                       //cors: cors install
npm i -D nodemon       //server restart when some change

3. package.json

Add ‘“start”: “nodemon app.js”

{
  "name": "blog_expressjs",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1",
    "start": "nodemon app.js"
  },
  "keywords": [],
  "author": "",
  "license": "ISC",
  "dependencies": {
    "express": "^4.17.1",
    "mongoose": "^5.11.8",
    "morgan": "^1.10.0"
  },
  "devDependencies": {
    "nodemon": "^2.0.6"
  }
}

When I will write the following command ‘’npm start’’ than ‘’npm nodemon app.js’’ will be run.

4. app.js

const express = require('express')
const cors = require("cors");
const morgan = require('morgan') //medillower function
const mongoose = require('mongoose')
const app = express() //route handaling,controller,templet  engine,middleware
app.use(morgan('dev')) //middleware
app.use(express.urlencoded({extended: true})) // for get form data
app.use(express.json())
app.use(cors())
app.get('/', (req, res) => {
 console.log("peyas")
 res.send("peyas")
})
mongoose.connect('mongodb://localhost:27017/test', {useNewUrlParser: true, useUnifiedTopology: true})
 .then(() => {
app.listen(4545, () => {
   console.log('Connected')
  })
})
 .catch(e => {
  console.log(e);
 })

Mongoose official website.(use this following tool we can easily connect with mongodb).

Mongoose

sudo systemctl status mongod
mongodb-compass

5. Run your project:

npm start

http://localhost:4545/