Introduction
Express was developed by independent developers
Installation
Step1:Create your node app
Give a name to your app and skip the rest of the values to get your first node project
npm init
Step2: Add some utilities
sudo npm install -g nodemon yarn
Step3: Create an express project using yarn package manager
yarn add express
Step4: Create your first server app
When you call hello from a browser, you will get a response
nodemon server.js
const express = require('express')
const app = express()
app.listen(4000, '0.0.0.0', () => {
console.log(`express server started successfully`)
})
app.get('/hello', (request, response) => {
response.send('Hello World')
})
Connect to DB
Step1: Download Robo 3T and connect it to your DB
Step2: Add yarn add mongoDB, and create a js file to connect to DB
const express = require('express')
const MongoClient = require('mongodb').MongoClient
const app = express()
app.get('/emp', (request, response) => {
// connect to the mongodb running on the local machine
MongoClient.connect('mongodb://localhost:27017/classwork', (err, client) => {
if (err) throw err
const db = client.db('classwork')
db.collection('emp')
.find()
.toArray((err, result) => {
if (err) throw err
response.send(result)
})
})
})
app.listen(4000, '0.0.0.0', () => {
console.log('server started on port 4000')
})
Add Routes
Step1: Create your App using the above, with routes file(routes.js) added to routes folder
const express = require('express')
const router = express.Router()
router.post('/signup', (request, response) => {
console.log(`name = ${request.body.name}`)
console.log(`email = ${request.body.email}`)
console.log(`password = ${request.body.password}`)
response.send('user signed up')
})
module.exports = router
Step2: Add route to the app server.js
const express = require('express')
const app = express()
app.use(express.json())
app.get('/', (request, response) => {
response.send('<h1>Welcome to the Application Backend</h1>')
})
const routerUser = require('./routes/user')
app.use(routerUser)
app.listen(4000, '0.0.0.0', () => {
console.log('server has started successfully on port 4000')
})
Step 3: Output from Postman
Create API with DB connectivity
SignUp with DB
Step1: Add Mongoose, and connect to DB
yarn add mongoose
const mongoose = require('mongoose')
mongoose.connect('mongodb://localhost:27017/tweeter')
Step2: Create user Model user.js inside models folder
const mongoose = require('mongoose')
const UserSchema = new mongoose.Schema({
name: String,
email: String,
password: String,
})
module.exports = mongoose.model('User', UserSchema)
Step3: Update SignUp endpoint
yarn add crypto-js for storing password Hash
const CryptoJs = require('crypto-js')
const utils = require('../utils')
router.post('/signup', (request, response) => {
const { name, email, password } = request.body
const user = new User()
user.name = name
user.email = email
user.password = `${CryptoJs.SHA256(password)}`
user.save((error, result) => {
response.send(utils.createResult(error, result))
})
})
Add util helper for handling response
function createResult(error, data) {
const result = {}
if (error) {
result['status'] = 'error'
result['error'] = error
} else {
result['status'] = 'success'
result['data'] = data
}
return result
}
module.exports = {
createResult,
}
Step4: Output for signup
SignIn with DB
Step1: Add the signing code
router.post('/signin', (request, response) => {
const { email, password } = request.body
User.findOne({ email: email, password: `${CryptoJs.SHA256(password)}` }).exec(
(error, user) => {
if (error) {
response.send({ status: 'error', error: error })
} else if (!user) {
response.send({ status: 'error', error: 'invalid email or password' })
} else {
response.send({ status: 'success', data: 'successfully logged in' })
}
}
)
})
Output
JWT tokens
yarn add jsonwebtoken
Step1 : Add Config file
const config = {
secret: 'b2VQXKIrB7urfisPxHuLss6Z2oTMR2MC',
}
module.exports = config
Step2 Add JSON web token when signed in
const jwt = require('jsonwebtoken')
const config = require('../config')
router.post('/signin', (request, response) => {
const { email, password } = request.body
User.findOne({ email: email, password: `${CryptoJs.SHA256(password)}` }).exec(
(error, user) => {
if (error) {
response.send({ status: 'error', error: error })
} else if (!user) {
response.send({ status: 'error', error: 'invalid email or password' })
} else {
// create payload which will be sent to the client
// and client will send it back every time while calling API
const payload = {
id: user._id,
}
// create jwt token
const token = jwt.sign(payload, config.secret)
// send the token to the user
response.send({
status: 'success',
data: {
email: user.email,
name: user.name,
token: token,
},
})
}
}
)
})
Step3 : output
