express: req.body: Get the request payload

‘req.body’ is used to get the request payload.

Let’s see it with an example.

index.js

const express = require('express')

const app = express()

const port = 3000

app.get('/', (req, res) => res.send("Hello World"))

app.post('/users', (req,res) => {
 console.log(`Received : ${req.body}`)
 res.status(201).send(`Received : ${req.body}`)
})

app.listen(port, () => console.log(`Application started listening on port ${port}!`));

Run index.js

Open postman and fire below post request.

Method: POST

url: http://localhost:3000/users

Body:

{

  "name" : "Krishna",

  "id" : "I12345"

}

Set the content-type header to application/json.

When I send the POST request, I got response as undefined.

Why req.body is undefined?

By default, req.body is undefined, and is populated when you use body-parsing middleware such as body-parser and multer.

How to use the body-parser?

Import body-parser api.

const bodyParser = require('body-parser');

Register the body-parser middlewares with express application.

// for parsing application/json

app.use(bodyParser.json());

// for parsing application/x-www-form-urlencoded

app.use(bodyParser.urlencoded({ extended: true }));

index.js

const express = require('express')
const bodyParser = require('body-parser');

const app = express()

// for parsing application/json
app.use(bodyParser.json()); 

// for parsing application/x-www-form-urlencoded
app.use(bodyParser.urlencoded({ extended: true })); 

app.get('/', (req, res) => res.send("Hello World"))

app.post('/users', (req,res) => {
 var receivedData = JSON.stringify(req.body, null, 0)
 console.log(`Received: ${receivedData}`)
 res.send(receivedData)
})

const port = 3000
app.listen(port, () => console.log(`Application started listening on port ${port}!`));

Run index.js

Hit the same POST request again.

You can see below message in console and postman.

Received: {"{\r\n  \"name\" : \"Krishna\",\r\n  \"id\" : \"I12345\"\r\n}\r\n\r\n":""}

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