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Description

This project consists of a NestJS application designed to manage seat bookings for an event, with a focus on concurrency and preventing race conditions. The application provides three main APIs to view available seats, book seats, and view seats booked by a specific user.

The application uses an in-memory database (e.g., an array or Map) to store seat availability and bookings, ensuring a lightweight and efficient solution. Optionally, you can integrate a database like PostgreSQL or SQLite. In your project, you used PostgreSQL in a Docker container without setting up volumes. This was done to ensure that when the container was stopped or removed, no data would be persisted, preventing any information from being stored on the computer where the container was running. As a result, all data would be lost when stopping the container, maintaining a clean environment for each run.

Dependencies

@nestjs/common, @nestjs/core - Core modules required for building a NestJS application.

@nestjs/platform-express - Integrates NestJS with the Express framework.

@nestjs/swagger & swagger-ui-express - Provides API documentation using OpenAPI (Swagger).

@nestjs/typeorm & typeorm - ORM for database management, facilitating integration with PostgreSQL.

class-validator & class-transformer - Used for validating and transforming request data.

pg - PostgreSQL client for Node.js, allowing interaction with the database.

reflect-metadata - Enables TypeScript decorators, which are essential for NestJS and TypeORM.

rxjs - Provides reactive programming utilities, commonly used in NestJS for handling asynchronous data.

Project setup

# Clone project
$ git clone https://github.com/Paulosouzx/SeatBooking

# install dependencies
$ npm install

# start database container
$ docker-compose up -d

Compile and run the project

# development
$ npm run start

# watch mode
$ npm run start:dev

You can test the services directly in Postman or access the automatic documentation via Swagger by visiting the /docs endpoint. When the service is started, a link will appear in the terminal, and you can copy it and paste it into your browser. This will redirect you to the Swagger interface, where you can explore the available endpoints and test the API interactively. This makes testing quick and easy, without needing to manually set up Postman.

API Endpoints

View Avaliable Seats

Endpoint: GET /api/seats

Retrieves a list of all available seats.

{
  "seats": [
    {
      "seatNumber": "A1",
      "status": "available"
    },
    {
      "seatNumber": "A2",
      "status": "booked"
    }
  ]
}

Book Seats

Endpoint: POST /api/seats

Books one or more seats for a specific user.

# Request Body
{
  "userId": "user123",
  "seatNumbers":
  ["A1", "A2"]
}

# Success Response
{
  "message": "Seats successfully booked.",
  "bookedSeats":
  ["A1", "A2"]
}

# Failure Response
{
  "message": "Some seats could not be booked.",
  "failedSeats": ["A2"],
  "bookedSeats": ["A1"]
}

View My Seats

Endpoint: GET /api/seats?userId={userId}

Displays all seats booked by the specified user.

{
  "userId": "user123",
  "bookedSeats": [
    {
      "seatNumber": "A1",
      "status": "booked"
    },
    {
      "seatNumber": "A3",
      "status": "booked"
    }
  ]
}

Conclusion

Learning NestJS has been an incredibly valuable experience. Before this, I had never really looked into this tool, but as I explored it, I realized how powerful and well-structured it is for backend development. I really enjoyed its modular approach, seamless integration with TypeScript, and the ease of working with concepts like dependency injection and validation.

Thank you for opportunity! :)