Express Starter App

This is a basic Express application that includes a URL shortener service. The application is written in JavaScript and uses npm for package management. This project implements a simple URL shortener service using Node.js, Express, and PostgreSQL.

Current Functionality

The application currently has two routes:

1. POST /shorten: This route accepts a URL and returns a shortened URL. Currently, it returns a static shortened URL.
2. GET /:shortUrl: This route accepts a shortened URL and redirects to a static URL.

The short URL mappings are stored in a PostgreSQL database.

Implemented Functionality

1. POST /shorten

• Accepts a JSON body containing a valid URL.
• Checks if the URL already exists in the database.
• If it does, returns the same short URL.
• If not, generates a new unique short code.
• Stores the short_url and original_url in the database.
• Returns the shortened URL.

2. GET /:shortUrl

• Looks up the short code in the database.
• Redirects to the original URL if found.
• Returns 404 if not found.

How to start

1. Open the repository in Codespaces

   Click Code → Create Codespace on main.

2. Install dependencies

• npm install
• sudo apt update
• sudo apt install -y postgresql-client

3. Start PostgreSQL using Docker (inside Codespaces)

   docker compose up -d

   Confirm it’s running: docker ps

4. Connect to PostgreSQL

   psql -U urluser -h localhost -d urlshortener

   Password: urlpass

5. Create the required table

   CREATE TABLE urls ( id SERIAL PRIMARY KEY, short_url VARCHAR(10) UNIQUE NOT NULL, original_url TEXT NOT NULL );

6. Start the application

   npm start

   Codespaces will prompt you to make port 3000 public.

   • Click Make Public → Open in Browser.

   • Copy the 3000 port URL for testing.

   • Your API base URL will look like: https://<your-id>-3000.app.github.dev

Testing the API with Postman

1. Test POST /shorten

   Method: POST

   Go to Ports and turn port 3000 public and copy the local address - this will be the URL:

   URL: https://<your-id>-3000.app.github.dev/shorten

   Body → raw → JSON { "url": "https://google.com" }

   Example Response:{ "shortUrl": "https://<your-id>-3000.app.github.dev/AbC123" }

   Sending "https://google.com" again returns the same short URL.

2. Test GET /:shortUrl

   Method: GET

   URL: https://<your-id>-3000.app.github.dev/AbC123

   Expected result: Redirect

   Browser takes you to https://google.com

   In Postman, turn Follow redirects OFF to see the redirect header.

3. Testing invalid inputs

   Missing body:

   {}

   Returns: 400 Bad Request

   Invalid URL: { "url": "not-a-url" }

   Returns: 400 Bad Request

Resetting the Database (Optional)

To delete all stored URLs: DELETE FROM urls;