Java Record as DTO in Spring Boot Application

In this section, we will show how we used Java Record as DTO in the Spring Boot application. The GitHub repository link is provided at the end of this tutorial. You can download the source code.

From Java 14 onwards, the record is a special type of class declaration aimed at reducing the boilerplate code.

Technologies used :

Spring Boot 2.6.3
Spring Data JPA
Java 17
H2 DB
Maven 3+

Let's do it,

Final Project Directory

Maven[pom.xml]

A Project Object Model or POM is the fundamental unit of work in Maven. It is an XML file that contains information about the project and configuration details utilized by Maven to build the project.

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" 
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 
    https://maven.apache.org/xsd/maven-4.0.0.xsd">

    <modelVersion>4.0.0</modelVersion>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.6.3</version>
        <relativePath />
    </parent>
    <groupId>spring-boot-java-record</groupId>
    <artifactId>spring-boot-java-record</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>spring-boot-java-record</name>
    <description>Demo project for Spring Boot</description>

    <properties>
        <java.version>17</java.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa
                </artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <!-- database -->
        <dependency>
            <groupId>com.h2database</groupId>
            <artifactId>h2</artifactId>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>

    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin
                </artifactId>
            </plugin>
        </plugins>
    </build>

</project>

Creating the Entity User

Records cannot be used as entities with JPA/Hibernate. JPA entities must have a no-args constructor, and must not be final, two requirements that the record will not support. More Information

package com.knf.dev.demo.springbootjavarecord.entity;

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.Table;

@Entity
@Table(name = "user")
public class User {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    private String firstName;
    private String lastName;
    private String email;

    public User() {
        super();
    }

    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public String getFirstName() {
        return firstName;
    }

    public void setFirstName(String firstName) {
        this.firstName = firstName;
    }

    public String getLastName() {
        return lastName;
    }

    public void setLastName(String lastName) {
        this.lastName = lastName;
    }

    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }

    public User(String firstName, 
       String lastName, String email) {
        super();
        this.firstName = firstName;
        this.lastName = lastName;
        this.email = email;
    }

}

Creating the User Repository

package com.knf.dev.demo.springbootjavarecord.repsitory;

import java.util.List;
import org.springframework.data.repository.CrudRepository;
import org.springframework.stereotype.Repository;
import com.knf.dev.demo.springbootjavarecord.entity.User;

@Repository
public interface UserRepository
        extends CrudRepository<User, Long> {
        List<User> findAll();
}

Creating the User Service

package com.knf.dev.demo.springbootjavarecord.service;

import java.util.List;
import java.util.Optional;
import java.util.stream.Collectors;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import com.knf.dev.demo.springbootjavarecord.dto.User;
import com.knf.dev.demo.springbootjavarecord.repsitory.UserRepository;

@Service
public class UserService {

    @Autowired
    UserRepository repsoitory ;

    //User mapper
    public User mapUser(com.knf.dev.demo.
        springbootjavarecord.
            entity.User user) {
        User userDto = new User(user.getId(), 
                          user.getFirstName(), 
                              user.getLastName(), 
                                  user.getEmail());
        return userDto;
    }

    public List<User> getAllUsers() {
        
        //Fetch all users
        List<com.knf.dev.demo.
        springbootjavarecord.
            entity.User> users = repsoitory.findAll();

        //converting list of user entity to
        // list of user record using java stream 
        return users.stream().
                map(this::mapUser).
                  collect(Collectors.toList());
    }

    public User getUserById(Long id) {

        // Fetch user by id
        Optional<com.knf.dev.demo.
            springbootjavarecord.
                entity.User> user 
        = repsoitory.findById(id);

        // converting user entity to
        // user record
        return mapUser(user.get());
    }
}