🏢 Basic Department API

A beginner-friendly REST API built with Spring Boot and H2 in-memory database to perform CRUD operations on Department data.

📚 Built while learning Spring Boot from Daily Code Buffer's Spring Boot Master Class

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🛠️ Tech Stack

Technology	Version	Purpose
Java	23	Programming Language
Spring Boot	4.0.3	Backend Framework
Spring Data JPA	4.0.3	Database ORM
H2 Database	2.4.240	In-memory Database
Hibernate	7.2.4	ORM Implementation
Lombok	1.18.42	Reduce boilerplate code
Maven	-	Build Tool

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📁 Project Structure

src/main/java/com/example/
├── controller/
│   ├── DepartmentController.java   ← Handles HTTP requests
│   └── HelloController.java
├── service/
│   ├── DepartmentService.java      ← Service interface
│   └── DepartmentServiceImpt.java  ← Business logic
├── Repository/
│   └── DepartmentRepository.java   ← Database layer
├── entity/
│   └── Department.java             ← Database entity
└── SpringBootTutorialApplication.java

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⚙️ Setup & Installation

Prerequisites

• Java 17+
• Maven
• IntelliJ IDEA (recommended)
• Postman (for API testing)

1. Clone the repository

git clone https://github.com/Karan-Rastogi/Basic-Department--Api.git
cd Basic-Department--Api

2. Run the project

mvn spring-boot:run

The server will start at: http://localhost:8082

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⚙️ Configuration (application.properties)

spring.datasource.url=jdbc:h2:mem:testdb
spring.datasource.driver-class-name=org.h2.Driver
spring.datasource.username=sa
spring.datasource.password=
spring.jpa.hibernate.ddl-auto=update
spring.h2.console.enabled=true
spring.h2.console.path=/h2-console
server.port=8082

H2 Console

Access the database UI at:

http://localhost:8082/h2-console

Field	Value
JDBC URL	jdbc:h2:mem:testdb
Username	sa
Password	(leave empty)

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🗂️ Department Entity

@Entity
@Data
public class Department {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long departmentId;
    private String departmentName;
    private String departmentAddress;
    private String departmentCode;
}

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🔗 API Endpoints

Method	Endpoint	Description
GET	/departments	Get all departments
GET	/departments/{id}	Get department by ID
GET	/departments/name/{name}	Get department by name
POST	/departments	Create new department
PUT	/departments/{id}	Update department
DELETE	/departments/{id}	Delete department

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🧪 Testing with Postman

Save a Department

POST http://localhost:8082/departments
Content-Type: application/json

{
    "departmentName": "Computer Science",
    "departmentAddress": "Delhi",
    "departmentCode": "CST"
}

Get All Departments

GET http://localhost:8082/departments

Get Department by ID

GET http://localhost:8082/departments/1

Get Department by Name

GET http://localhost:8082/departments/name/Computer Science

Update Department

PUT http://localhost:8082/departments/1
Content-Type: application/json

{
    "departmentName": "Information Technology",
    "departmentAddress": "Mumbai",
    "departmentCode": "IT"
}

Delete Department

DELETE http://localhost:8082/departments/1

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🗂️ Layer Explanation

Layer	File	Responsibility
Controller	DepartmentController.java	Handles HTTP requests & responses
Service	DepartmentServiceImpt.java	Contains business logic
Repository	DepartmentRepository.java	Talks to H2 database
Entity	Department.java	Maps to database table

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📚 What I Learned

• Spring Boot project structure (Controller → Service → Repository → Entity)
• How REST APIs work with HTTP methods (GET, POST, PUT, DELETE)
• Connecting Spring Boot with H2 in-memory database
• Using Spring Data JPA and Hibernate ORM
• Using Lombok to reduce boilerplate code
• Testing APIs with Postman
• Version control with Git and GitHub

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🚀 Future Improvements

• Migrate from H2 to MySQL database
• Add exception handling with @ControllerAdvice
• Add input validation with @Valid
• Add pagination and sorting
• Add unit tests with JUnit and Mockito
• Add Spring Security with JWT authentication

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👨‍💻 Author

Karan Rastogi

• GitHub: @Karan-Rastogi

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