Building a URL shortener service with Express.js and Redis

17 Sep 2023

URL shorteners are essential tools that allow us to shorten long URLs into more manageable and shareable links. In this blog post, we will explore how to build a URL shortener service using Express.js and Redis, a powerful in-memory data store.

Prerequisites

Before we dive into the implementation, make sure you have the following prerequisites installed on your machine:

Node.js and npm
Express.js
Redis

Setting up the project

To get started, let’s create a new directory for our project and initialize a new Node.js project. Open your terminal and run the following commands:

mkdir url-shortener
cd url-shortener
npm init -y

Next, let’s install the necessary dependencies: Express.js and Redis.

npm install express redis

Creating the Express.js app

Now that we have our project set up, let’s create the main file index.js and set up our Express.js app.

const express = require('express');
const redis = require('redis');

const app = express();
const client = redis.createClient();

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

// TODO: Define routes

app.listen(3000, () => {
  console.log('Server is running on port 3000');
});

In the code snippet above, we imported express and redis libraries and created an instance of both express and redis clients. We also set up the necessary middleware to parse JSON and URL-encoded data.

Shortening URLs

To shorten a URL, we need to define a route that accepts a long URL and generates a unique short code for it.

app.post('/shorten', (req, res) => {
  const { longUrl } = req.body;
  const shortCode = generateShortCode();

  client.set(shortCode, longUrl, (err) => {
    if (err) {
      res.status(500).json({ message: 'Failed to shorten URL' });
    } else {
      res.status(200).json({ shortUrl: `https://example.com/${shortCode}` });
    }
  });
});

In this code, we define a POST route /shorten that extracts the longUrl from the request body. We generate a unique shortCode and use client.set() function provided by Redis client to store the mapping of shortCode and longUrl.

Redirecting to original URLs

To redirect users to the original URL when they access the shortened URL, we define another route that accepts the shortCode.

app.get('/:shortCode', (req, res) => {
  const { shortCode } = req.params;

  client.get(shortCode, (err, longUrl) => {
    if (err || !longUrl) {
      res.status(404).json({ message: 'URL not found' });
    } else {
      res.redirect(longUrl);
    }
  });
});

Here, we define a GET route /:shortCode and use client.get() to retrieve the corresponding longUrl. If the longUrl exists, we redirect the user to it; otherwise, we return a 404 status code.

Conclusion

In this blog post, we explored how to build a URL shortener service using Express.js and Redis. Redis provides fast and efficient data storage, while Express.js enables us to easily define routes and handle HTTP requests. By combining these technologies, we can build a robust and scalable URL shortener service. Remember to optimize your code and handle edge cases for a production-ready implementation.

#hashtags: #ExpressJS #Redis