Read-only transactions in Spring Boot - Mini Project: Build & Apply

Read-only transactions in Spring Boot

📖 Scenario: You are building a simple Spring Boot application that fetches user data from a database. To ensure data safety and optimize performance, you want to mark your service method as a read-only transaction.

🎯 Goal: Create a Spring Boot service method that uses a read-only transaction annotation to fetch user data safely without allowing any data changes.

📋 What You'll Learn

Create a service class called UserService.

Add a method called getAllUsers that returns a list of users.

Configure the getAllUsers method with a read-only transaction using @Transactional(readOnly = true).

Use a repository called UserRepository with a method findAll() to fetch users.

💡 Why This Matters

🌍 Real World

Read-only transactions are used in real applications to safely fetch data without risking accidental changes, improving performance and data integrity.

💼 Career

Understanding how to use read-only transactions is important for backend developers working with Spring Boot to write efficient and safe database access code.

1

Create UserService class with getAllUsers method

Create a class called UserService with a method getAllUsers that returns a List<User>. Do not add any annotations yet.

Spring Boot

public class UserService {
    // Your code here
}

Need a hint?

Define the class and method signature first. Return null for now.

2

Add UserRepository field and constructor

Add a private final field UserRepository userRepository to UserService. Create a constructor that accepts UserRepository userRepository and assigns it to the field.

Spring Boot

import java.util.List;

public class UserService {
    private final UserRepository userRepository;

    // Your code here

    public List getAllUsers() {
        // Your code here
        return null;
    }
}

Need a hint?

Add the repository field and constructor for dependency injection.

3

Implement getAllUsers method to fetch users

In getAllUsers, return the result of userRepository.findAll().

Spring Boot

import java.util.List;

public class UserService {
    private final UserRepository userRepository;

    public UserService(UserRepository userRepository) {
        this.userRepository = userRepository;
    }

    public List getAllUsers() {
        // Return all users from repository
        // Your code here
    }
}

Need a hint?

Call the repository's findAll method and return its result.

4

Add @Transactional(readOnly = true) annotation

Add the annotation @Transactional(readOnly = true) above the getAllUsers method to mark it as a read-only transaction. Import org.springframework.transaction.annotation.Transactional.

Spring Boot

import java.util.List;
import org.springframework.transaction.annotation.Transactional;

public class UserService {
    private final UserRepository userRepository;

    public UserService(UserRepository userRepository) {
        this.userRepository = userRepository;
    }

    // Add @Transactional(readOnly = true) here
    public List getAllUsers() {
        return userRepository.findAll();
    }
}

Need a hint?

Use the @Transactional annotation with readOnly = true on the method.