CRUD methods (save, findById, findAll, delete) in Spring Boot - Mini Project: Build & Apply

CRUD methods (save, findById, findAll, delete) in Spring Boot

📖 Scenario: You are building a simple Spring Boot application to manage a list of books in a library. Each book has an ID, title, and author.We want to create basic CRUD (Create, Read, Update, Delete) methods to save a book, find a book by its ID, find all books, and delete a book by its ID.

🎯 Goal: Build a Spring Boot repository interface with CRUD methods: save, findById, findAll, and deleteById for managing books.

📋 What You'll Learn

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

Create a BookRepository interface extending JpaRepository

Use save method to add or update a book

Use findById method to get a book by its ID

Use findAll method to get all books

Use deleteById method to remove a book by its ID

💡 Why This Matters

🌍 Real World

Managing data records in applications like libraries, stores, or user management systems requires CRUD operations to create, read, update, and delete data.

💼 Career

Understanding CRUD methods with Spring Boot and JPA is essential for backend developers working on Java web applications and APIs.

1

Create the Book entity class

Create a Java class called Book in package com.example.library with private fields Long id, String title, and String author. Add @Entity annotation and use @Id and @GeneratedValue on the id field.

Spring Boot

package com.example.library;

// Your code here

Need a hint?

Use @Entity on the class and @Id with @GeneratedValue on the id field.

2

Create the BookRepository interface

Create an interface called BookRepository in package com.example.library that extends JpaRepository<Book, Long>.

Spring Boot

package com.example.library;

// Your code here

Need a hint?

Extend JpaRepository with Book as entity and Long as ID type.

3

Use save and findById methods

In a service class called BookService in package com.example.library, inject BookRepository and write a method saveBook(Book book) that calls bookRepository.save(book). Also write a method findBookById(Long id) that returns bookRepository.findById(id).

Spring Boot

package com.example.library;

import org.springframework.stereotype.Service;
import java.util.Optional;

// Your code here

Need a hint?

Inject BookRepository via constructor and use its save and findById methods.

4

Add findAll and deleteById methods

In the BookService class, add a method findAllBooks() that returns bookRepository.findAll(). Also add a method deleteBookById(Long id) that calls bookRepository.deleteById(id).

Spring Boot

package com.example.library;

import java.util.List;

// Your code here

Need a hint?

Use findAll() to get all books and deleteById(id) to remove a book by ID.