Nested DTOs in Spring Boot - Mini Project: Build & Apply

Nested DTOs in Spring Boot

📖 Scenario: You are building a simple Spring Boot application to manage books and their authors. Each book has a title and an author. The author has a name and an email.

🎯 Goal: Create nested DTO (Data Transfer Object) classes to represent a BookDTO that contains an AuthorDTO. This helps organize data cleanly when sending or receiving JSON in your application.

📋 What You'll Learn

Create a class AuthorDTO with fields name and email.

Create a class BookDTO with fields title and author of type AuthorDTO.

Use Java records to define these DTOs for simplicity.

Ensure the nested structure is correct for JSON serialization.

💡 Why This Matters

🌍 Real World

Nested DTOs are common in web APIs where objects contain other objects, like a book containing an author. This helps keep data organized and easy to manage.

💼 Career

Understanding nested DTOs is essential for backend developers working with Spring Boot to build clean, maintainable APIs that handle complex data structures.

1

Create the AuthorDTO record

Create a Java record called AuthorDTO with two fields: String name and String email.

Spring Boot

// Your code here

Need a hint?

Use the record keyword to create a simple immutable data class with the specified fields.

2

Create the BookDTO record with nested AuthorDTO

Create a Java record called BookDTO with two fields: String title and AuthorDTO author. Use the previously created AuthorDTO as the type for the author field.

Spring Boot

public record AuthorDTO(String name, String email) {
}

// Your code here

Need a hint?

Use the AuthorDTO type inside BookDTO to nest the author information.

3

Create an instance of AuthorDTO

Create a variable called author and assign it a new AuthorDTO instance with name set to "Jane Austen" and email set to "[e-mail]".

Spring Boot

public record AuthorDTO(String name, String email) {
}

public record BookDTO(String title, AuthorDTO author) {
}

// Your code here

Need a hint?

Use the new keyword to create an instance of the AuthorDTO record with the exact values.

4

Create an instance of BookDTO using the nested AuthorDTO

Create a variable called book and assign it a new BookDTO instance with title set to "Pride and Prejudice" and author set to the previously created author variable.

Spring Boot

public record AuthorDTO(String name, String email) {
}

public record BookDTO(String title, AuthorDTO author) {
}

AuthorDTO author = new AuthorDTO("Jane Austen", "[e-mail]");

// Your code here

Need a hint?

Use the author variable as the second argument when creating the BookDTO instance.