Mastering Request Body Parsing in Express.js with Body-parser Middleware

Mastering Request Body Parsing in Express.js with Body-parser Middleware


3 min read

Hello, fellow developers! πŸ‘‹

In this post, I will share with you how to use body-parser, a popular middleware that helps us parse the request body in Express.js. If you have ever encountered the problem of req.body being undefined, this post is for you. 😊

What is req.body and why do we need body-parser?

The request body is a byte stream that contains the data sent by the client to the server. It can be anything, such as JSON, URL-encoded, text, or raw data. For example, when you submit a form on a website, the form data is sent as the request body to the server.

However, Express.js does not parse the request body by default. It just passes it as a raw stream to the next middleware. This means that if you try to access req.body in your route handler, you will get undefined.

That's where body-parser comes in. Body-parser is a middleware that can decode and parse different types of request bodies into JavaScript objects. This way, you can access the client's data in your server using req.body.

How to use body-parser?

To use body-parser, you need to install it using npm install body-parser and then import it in your app using const bodyParser = require('body-parser').

Then, you need to use it as a middleware before your route handlers. You can choose different methods of body-parser depending on the type of request body you want to parse. Here are some common use cases:

  • To parse JSON: app.use(bodyParser.json())
  • To parse URL-encoded: app.use(bodyParser.urlencoded({ extended: false }))
  • To parse text: app.use(bodyParser.text())
  • To parse raw: app.use(bodyParser.raw())

You can also specify some options for each method, such as limit, type, or verify. You can check the [documentation] for more details.

After using body-parser as a middleware, you can access the client's data in your route handler using req.body. For example:'/users', (req, res) => {
  console.log(req.body); // { name: 'John', age: 25 }
  // do something with req.body

What are some alternative to body parser?

Body-parser is not the only middleware that can parse the request body in Express.js. There are some alternatives that you can use depending on your needs and preferences. Here are some of them:

  • Express built-in middleware: Since version 4.16.0, Express has included some built-in middleware functions that can parse JSON and URL-encoded request bodies. You can use them by calling
    app.use(express.json()) or app.use(express.urlencoded({ extended: false }));
    However, they do not support other types of request bodies like text or raw.

Learn more about body-parser Click here


That’s it for this post on body-parser, a middleware that helps us parse the request body in Express.js. I hope you learned something new and useful. If you did, please like and share this post and let me know your thoughts in the comments. I’m always happy to connect with fellow developers. 😊

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