📚 Book Management API

Made to learn implementation of REST API in Java and DTO Model Conversion.

Overview

This is a simple Spring Boot REST API for managing books, in this scenario for library.

It demonstrates clean separation of Model and DTO, validation with @Valid, and the use of H2 for the database.

Tech Stack

• Java 17+
• Spring Boot (Web, Validation, Data JPA)
• Lombok (for @Data, @RestContoller, and etc.)
• H2 Database (In-memory for testing)
• Maven (Dependency Management)

Key Concepts Learned

Model

Part of program that represents the actual database entity. Code is here

---

DTO (Data Transfer Object)

A simpler version of object, used to send/receive data in API calls. It prevents exposing the full database structure and allow customizing request/response fields. Code is here

Flow of Data

Request -> Controller -> Service -> Repository -> Database and back.

Example Scenario:

1. User sends POST /books with JSON Body

{
	"title": "The Hobbit",
    "author": "J.R. Tolkien",
    "quantity": 30
}

2. Controller receives BookDTO (@Valid runs validation).
3. Service converts DTO to Model
4. Repository saves Model to DB
5. Response is sent back as BookDTO

{
    "title": "The Hobbit",
    "author": "J.R. Tolkien",
    "quantity": 30
}