Getting Data From req.body in Node.js & Express Server | WM

A Node.js and Express server can receive data from a client in many ways. Typically when a user sends a POST request also sends some data in the request body. The server needs to extract that information from the request body.

The body-parser package is used to get data from the request body in an Express server. After setting up this package as a middleware function, it will extract information passed by a user and store it in the req.body object. Any route can access the data from that object.

From the client side, a user submits a form that sends a POST request with the information from the form inputs. They can also use other HTTP clients like Axios or the fetch() method in JavaScript to send data to the server.

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In this lesson, you will learn how to extract those data from the request and access it through the req.body object inside a Node.js and Express server.

You can also use URL query strings and parameters in Express to get information from users to your server. But you have to follow techniques to extract them.

Install body-parser Package to Get Data From req.body

To use the body-parser package, you need to have an Express server. If you don’t have the server, you can follow our best setup guide for an Express server with TypeScript.

Now, you need to install this package inside your project. You can install this package using the following command:

          npm install body-parser
        

You can use it after the installation by importing this package into your project. Let’s see how to apply it as a middleware function and get data in Express.

How to Get Data From Request Body in Express

The body-parser package parsers the JSON, raw buffer data, plain text, and URL-encoded data like x-www-form-urlencoded content type.

Most of the time, we parse JSON and URL-encoded data in our servers. For that, you have to use two methods from this package to handle these two types of data.

For JSON data:

          app.use(bodyParser.json());
        

This json() method will parse any type of JSON data from the request body in the Express server. If you know that your server will only get data in a JSON format from the users, you will use this method.

If the client uses the fetch() API or Axios to send the request, they set the content-type header as application/json because they send data in JSON format.

For URL-encoded data:

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

If the users send POST requests by submitting a form, it will use application/x-www-form-urlencoded as the content-type to send the data. To parse that from the request body, we need to use the urlencoded() method.

With the extended option, you can choose between the query-string library or the qs library to parse the URL-encoded data. You can set this option as true or false.

Note: The query-string library can not create a nasted object from the data. But the qs library can create a nested object.

If it is set to false then the urlencoded() method will use the query-string library. When the extended is true, this method will use the qs library. You can choose any one of them.

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

const app = express();

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

app.get('/', (req, res) => {
    res.send('Home page');
});

app.post('/login', (req, res) => {
    console.log(req.body.email);
    console.log(req.body.password);

    // validate email and password here

    res.redirect('/dashboard');
});

app.get('/dashboard', (req, res) => {
    res.send('Dashboard page');
});

const PORT = process.env.PORT || 3000;

app.listen(PORT, () => {
    console.log(`server listening on ${PORT}`);
});
        

I am getting the package and using both urlencoded() and json() methods so that I can parse JSON and URL-encoded data in my server.

Now I will be able to access any data from the request body using the req.body object. In this example, I have a POST /login route where a user will send email and password to log in.

I will get those data from the req.body and validate the data. If the information is correct, it will redirect to another route using the Express res.redirect() method.

Now you know why and how we get data from the request body in the Express server.

Conclusion

As you know, we can use URL query strings and parameters to transfer data from a client to the server. But it has a limited capacity. To exchange a large amount of data between the client and server, we use the POST method.

To extract that data from the request, we use the body-parse middleware functions. They convert the data into a JavaScript object and add it to the req.body so that we can get the values.

In this article, we have discussed parsing and getting data from the POST request body using the req.body object in Express and Node.js server.