Database and app orchestration in Spring Boot - Mini Project: Build & Apply

Database and App Orchestration with Spring Boot

📖 Scenario: You are building a simple Spring Boot application that manages a list of books. Each book has a title and an author. You will create the data model, configure the database connection, implement the repository to interact with the database, and finally create a REST controller to expose the data.

🎯 Goal: Build a Spring Boot application that connects to an in-memory H2 database, stores book data, and exposes a REST API to retrieve the list of books.

📋 What You'll Learn

Create a Book entity with fields id, title, and author

Configure the application to use H2 in-memory database

Create a Spring Data JPA repository interface for Book

Create a REST controller with a GET endpoint /books to return all books

💡 Why This Matters

🌍 Real World

This project simulates a common real-world scenario where a backend application manages data stored in a database and exposes it via REST APIs for frontend or other services to consume.

💼 Career

Understanding how to orchestrate database entities, repositories, and REST controllers in Spring Boot is essential for backend development roles and building full-stack applications.

1

Create the Book entity

Create a Java class called Book in package com.example.demo with fields Long id, String title, and String author. Annotate it with @Entity. Use @Id and @GeneratedValue on the id field.

Spring Boot

package com.example.demo;

// Your code here

Need a hint?

Use @Entity to mark the class as a database entity. Use @Id and @GeneratedValue on the id field.

2

Configure H2 database in application.properties

Add the following lines to src/main/resources/application.properties to configure the H2 in-memory database and enable the H2 console: spring.datasource.url=jdbc:h2:mem:testdb, spring.datasource.driverClassName=org.h2.Driver, spring.datasource.username=sa, spring.datasource.password=, spring.jpa.database-platform=org.hibernate.dialect.H2Dialect, and spring.h2.console.enabled=true.

Spring Boot

package com.example.demo;

import jakarta.persistence.Entity;
import jakarta.persistence.Id;
import jakarta.persistence.GeneratedValue;
import jakarta.persistence.GenerationType;

@Entity
public class Book {
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Long id;
    private String title;
    private String author;

    public Book() {}

    public Book(String title, String author) {
        this.title = title;
        this.author = author;
    }

    public Long getId() {
        return id;
    }

    public String getTitle() {
        return title;
    }

    public void setTitle(String title) {
        this.title = title;
    }

    public String getAuthor() {
        return author;
    }

    public void setAuthor(String author) {
        this.author = author;
    }
}

# Add these lines to src/main/resources/application.properties
# Your code here

Need a hint?

Configure the H2 database URL and enable the H2 console for easy database access.

3

Create the BookRepository interface

Create an interface called BookRepository in package com.example.demo that extends JpaRepository<Book, Long>. This interface will allow database operations on the Book entity.

Spring Boot

package com.example.demo;

import org.springframework.data.jpa.repository.JpaRepository;

// Your code here

Need a hint?

Extend JpaRepository with the entity Book and primary key type Long.

4

Create the BookController REST API

Create a class called BookController in package com.example.demo. Annotate it with @RestController. Inject BookRepository via constructor. Add a GET mapping for /books that returns List<Book> by calling bookRepository.findAll().

Spring Boot

package com.example.demo;

import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.bind.annotation.GetMapping;
import java.util.List;

// Your code here

Need a hint?

Use @RestController and @GetMapping("/books"). Inject the repository via constructor.