Category: POST request

Develop a POST and GET request to add and get data from a file in nodejs

So far, we’ve learnt developing nodejs API with GET and POST request in json format. Today, let’s raise our learning bar and learn saving or writing the json data to a file.

Since, nodejs has huge repository of node modules, it makes our life pretty easy to do almost anything just by importing the respective module.

For instance, in this post, we are going to save the json data to a file for which we need a file stream library that enables us to read and write the data. With nodejs, it is just simple to accomplish this. All you need to do is, install the ‘fs’ module using npm(Node Package Manager) using following command in terminal:

npm install fs
Similarly, body parser is used to extract the entire body portion of an incoming request stream which is exposed on req.body. You may install it using following command:
npm install body-parser

Let’s first add the user data which includes the user name, profession and password. Since, we require the user’s input here, let’s use POST request to send these parameters.

Here, I am saving the data to a file named users.json


var express = require('express');

var app = express();

var fs = require("fs");

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

app.use(bodyParser.json({limit: '5mb'}));//set the limit of maximum request body size

app.use( bodyParser.json() );       // to support JSON-encoded bodies

app.use(bodyParser.urlencoded({     // to support URL-encoded bodies

        extended: true,

        limit: '5mb'



//saving the user to file'/addUser', function (req, res) {

    // First read the parameters sent through body.

    var name =;

    var password = req.body.password;

    var profession = req.body.profession;

//creating a JSON object with the received parameters.

    var user = {

        "user1" : {

            "name" : name,

            "password" : password,

            "profession" : profession,

            "id": 1



user = JSON.stringify(user);

fs.writeFile('users.json', user);


res.json({'message' : 'User added', 'details' : JSON.parse(user) });


//To list the saved users, here's a GET request

app.get('/listUser', function (req, res) {

    // First read existing users.

    fs.readFile( __dirname + "/" + "users.json", 'utf8', function (err, data) {

        data = JSON.parse( data );

        console.log( data );




// set a port for the server to listen

var server = app.listen(8081, function () {

    var port = server.address().port

    console.log("Example app listening at http://localhost:%s", port)


Now let’s run the server to save the user data:

node server.js

Example app listening at http://localhost:8081

To insert the data, send a POST request, you may send the data through form-data or use third party REST client apps like REST client, Http Request or Post Master.

I have used a HTML form to add the user

Here’s the HTML code :


<title>Add user</title>


<form  action="http://localhost:8081/addUser" method="post">

  <input value = "name" type="name" name="name" />

  <input value = "profession" type="profession" name="profession" />

  <input value = "password" type="password" name="password" />

  <input type="submit" value="Add"  name="submit" />

  <input type="reset" value="Clear"/>





Here the data is inserted to users.json file now. To fetch the data from file, we use GET request.

Enter the url “http://localhost:8081/listUser” in your browser and it lists the users in the file.

That’s it! Hope this was of help. Happy coding!

Developing a POST request in nodejs

Unlike GET request which sends the data through URL may not be considered the right option in case of sending a confidential data, POST request is considered the best option as it encrypts the data in the body to send it.

Nodejs is a one of a kind where you can easily create a POST request. Let’s learn how to create a POST request.

1. We will create a request to get the user name. Let’s name the server file as server.js


var express = require('express');

var app = express();

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

// Create application/x-www-form-urlencoded parser

var urlencodedParser = bodyParser.urlencoded({ extended: false })

//The / here represents the path to an interface to send the user name from

    app.get('/', function (req, res) {

        res.sendFile( __dirname + "/" + "index.html" );

    })'/listUsers', urlencodedParser, function (req, res) {

    // Prepare output in JSON format

    response = {








console.log("server is up and running..");

The express module enables you to create a server while the body parser allows you to parse the body in which the user name is sent. Since we need to encode the body, the urlencoded does the job for us.

The post request uses headers to send the data, you may need different types of headers depending upon your requirement(for instance, multipart-form-data to send files and x-www-form-urlencoded to send form data). For more info about headers, click here

req.body refers to the content of the body. If you’d like to fetch specific contents from the body, you may add it at the end of req.body as in the above code where we’re fetching first_name using req.body.first_name.

2. To send a request, we first create an interface where we can send the username from.




<form action = "http://localhost:8081/listUsers" method = "POST">

 First Name: <input type = "text" name = "first_name">&nbsp; <br>

 Last Name: <input type = "text" name = "last_name">

 <input type = "submit" value = "Submit">



3. Running the server

Now that we are ready with server and interface, let’s run them.

To run the node server, type the following command(presuming you have nodejs installed or you may install it from here)



server is up and running..

4. To send a request using the interface, open http:localhost:8081 in your browser and you will be redirected to webpage where you can input username

4. Click on “Submit“, which sends a request to the server and you’ll get response that returns the username

If you notice the url in the output, you don’t find the user name unlike in GET request you’ll find the user name in the URL itself. The user name in POST request in embedded in the body which is why it doesn’t appear in the URL. Thus, POST request is considered to be the best practice while sending confidential data.

Here we are representing them in JSON format. Similarly, we may save it to the file or database which I’ll demonstrate in the upcoming posts.

Happy coding! 😉