Event Booking System

A Mini Event Management System built with Node.js, Express, and MySQL.

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Tech Stack

• Runtime: Node.js
• Framework: Express.js
• Database: MySQL 8
• Validation: express-validator
• Docs: OpenAPI 3.0 / Swagger UI
• Other: uuid, dotenv, mysql2

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Project Structure

event-booking-system/
├── src/
│   ├── app.js                        # Entry point
│   ├── config/
│   │   └── db.js                     # MySQL connection pool
│   ├── controllers/
│   │   ├── eventController.js
│   │   ├── bookingController.js
│   │   └── attendanceController.js
│   ├── routes/
│   │   ├── eventRoutes.js
│   │   ├── bookingRoutes.js
│   │   ├── userRoutes.js
│   │   └── attendanceRoutes.js
│   └── middleware/
│       ├── errorHandler.js
│       └── validate.js
├── docs/
│   └── swagger.yaml                  # OpenAPI spec
├── schema.sql                        # Database schema + seed data
├── postman_collection.json
├── Dockerfile
├── docker-compose.yml
├── .env.example
└── README.md

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Option A — Run with Docker (Recommended)

One command starts both MySQL and the API server.

Prerequisites

• Docker
• Docker Compose

Steps

# 1. Clone the repository
git clone <your-repo-url>
cd event-booking-system

# 2. Start everything
docker-compose up --build

# API is live at:  http://localhost:3000
# Swagger docs at: http://localhost:3000/api-docs

To stop:

docker-compose down

To stop and wipe the database volume:

docker-compose down -v

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Option B — Run Locally

Prerequisites

• Node.js >= 18
• MySQL 8 running locally

Steps

# 1. Clone the repository
git clone <your-repo-url>
cd event-booking-system

# 2. Install dependencies
npm install

# 3. Configure environment variables
cp .env.example .env
# Edit .env and fill in your MySQL credentials

# 4. Set up the database
mysql -u root -p < schema.sql
# This creates the database, tables, and seed data

# 5. Start the server
npm start          # production
npm run dev        # development (nodemon, auto-reload)

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Environment Variables

Variable	Default	Description
PORT	3000	HTTP port
DB_HOST	localhost	MySQL host
DB_PORT	3306	MySQL port
DB_USER	root	MySQL username
DB_PASSWORD	(empty)	MySQL password
DB_NAME	event_booking_db	MySQL database name

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API Endpoints

Method	Endpoint	Description
GET	/events	List all upcoming events
POST	/events	Create a new event
POST	/bookings	Book a ticket (transactional, race-safe)
GET	/users/:id/bookings	Get all bookings for a user
POST	/events/:id/attendance	Record attendance using a booking code
GET	/health	Health check

Full interactive documentation: http://localhost:3000/api-docs

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Key Design Decisions

Race Condition Prevention

POST /bookings uses a MySQL transaction with SELECT … FOR UPDATE to lock the event row before decrementing remaining_tickets. This ensures that two simultaneous requests cannot both read remaining_tickets = 1 and both succeed.

Unique Booking Code

Each booking receives a UUID v4 as its booking_code. This is returned to the user post-booking and is required for event check-in via /events/:id/attendance.

Duplicate Entry Prevention

• A user cannot book the same event twice (UNIQUE KEY uq_user_event).
• A booking code cannot be used for entry more than once (UNIQUE KEY uq_attendance_booking).

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Running the Postman Collection

1. Open Postman
2. Click Import → select postman_collection.json
3. Set the baseUrl variable to http://localhost:3000 (already set by default)
4. Run requests in order: create event → book ticket → copy booking_code → record attendance

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Database Schema Export

The schema.sql file contains the full schema with all tables, constraints, and seed data.

To re-export after making changes:

mysqldump -u root -p --no-data event_booking_db > schema.sql