Spring Boot DTO ModelMapper Example

In this previous example, we have seen how to use DTO in Spring boot application and we have written a code to manually convert Entity to DTO. In this example, we will see how to use ModelMapper library to automatically convert Entity to DTO and vice-versa.

Here are the simple steps to follow to use ModelMapper library in Spring boot application.

The source code of this tutorial available on our GitHub repository at https://github.com/RameshMF/springboot-dto-tutorial

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1. Add ModelMapper Dependency

Open pom.xml file and add the following ModelMapper dependency:

		<!-- https://mvnrepository.com/artifact/org.modelmapper/modelmapper -->
		<dependency>
			<groupId>org.modelmapper</groupId>
			<artifactId>modelmapper</artifactId>
			<version>2.4.4</version>
		</dependency>

Here is the complete pom.xml for your reference:

<?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>2.5.4</version>
		<relativePath/> <!-- lookup parent from repository -->
	</parent>
	<groupId>net.javaguides</groupId>
	<artifactId>springboot-dto-tutorial</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<name>springboot-dto-tutorial</name>
	<description>Demo project for Spring Boot and DTO</description>
	<properties>
		<java.version>11</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>

		<dependency>
			<groupId>com.h2database</groupId>
			<artifactId>h2</artifactId>
			<scope>runtime</scope>
		</dependency>
		<dependency>
			<groupId>org.projectlombok</groupId>
			<artifactId>lombok</artifactId>
			<optional>true</optional>
		</dependency>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-test</artifactId>
			<scope>test</scope>
		</dependency>
		<!-- https://mvnrepository.com/artifact/org.modelmapper/modelmapper -->
		<dependency>
			<groupId>org.modelmapper</groupId>
			<artifactId>modelmapper</artifactId>
			<version>2.4.4</version>
		</dependency>
	</dependencies>

	<build>
		<plugins>
			<plugin>
				<groupId>org.springframework.boot</groupId>
				<artifactId>spring-boot-maven-plugin</artifactId>
				<configuration>
					<excludes>
						<exclude>
							<groupId>org.projectlombok</groupId>
							<artifactId>lombok</artifactId>
						</exclude>
					</excludes>
				</configuration>
			</plugin>
		</plugins>
	</build>

</project>

2. Configure ModelMapper as Spring Bean

Open Spring boot main application class and add the following ModelMapper bean configuration:

	@Bean
	public ModelMapper modelMapper(){
		return new ModelMapper();
	}

Here is the complete code:

package net.javaguides.springboot;

import net.javaguides.springboot.model.Location;
import net.javaguides.springboot.model.User;
import net.javaguides.springboot.repository.LocationRepository;
import net.javaguides.springboot.repository.UserRepository;
import org.modelmapper.ModelMapper;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.CommandLineRunner;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.Bean;

@SpringBootApplication
public class SpringbootDtoTutorialApplication implements CommandLineRunner {

	@Bean
	public ModelMapper modelMapper(){
		return new ModelMapper();
	}

	public static void main(String[] args) {
		SpringApplication.run(SpringbootDtoTutorialApplication.class, args);
	}

	@Autowired
	private UserRepository userRepository;

	@Autowired
	private LocationRepository locationRepository;

	@Override
	public void run(String... args) throws Exception {

		Location location = new Location();
		location.setPlace("Pune");
		location.setDescription("Pune is great place to live");
		location.setLongitude(40.5);
		location.setLatitude(30.6);
		locationRepository.save(location);

		User user1 = new User();
		user1.setFirstName("Ramesh");
		user1.setLastName("Fadatare");
		user1.setEmail("ramesh@gmail.com");
		user1.setPassword("secret");
		user1.setLocation(location);
		userRepository.save(user1);

		User user2 = new User();
		user2.setFirstName("John");
		user2.setLastName("Cena");
		user2.setEmail("john@gmail.com");
		user2.setPassword("secret");
		user2.setLocation(location);
		userRepository.save(user2);

	}
}

3. Inject or Autowire ModelMapper Bean in Service Class

Let's inject or autowire ModelMapper bean to use it's methods:

    @Autowired
    private UserRepository userRepository;

Here is the complete code:

package net.javaguides.springboot.service;

import net.javaguides.springboot.dto.UserLocationDTO;
import net.javaguides.springboot.model.User;
import net.javaguides.springboot.repository.UserRepository;
import org.modelmapper.ModelMapper;
import org.modelmapper.convention.MatchingStrategies;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import java.util.List;
import java.util.stream.Collectors;

@Service
public class UserService {

    @Autowired
    private UserRepository userRepository;

    @Autowired
    private ModelMapper modelMapper;

   // ....
}

4. Convert Entity to DTO and Vice-Versa using ModelMapper

    private UserLocationDTO convertEntityToDto(User user){
        modelMapper.getConfiguration()
                .setMatchingStrategy(MatchingStrategies.LOOSE);
        UserLocationDTO userLocationDTO = new UserLocationDTO();
        userLocationDTO = modelMapper.map(user, UserLocationDTO.class);
        return userLocationDTO;
    }

    private User convertDtoToEntity(UserLocationDTO userLocationDTO){
        modelMapper.getConfiguration()
                .setMatchingStrategy(MatchingStrategies.LOOSE);
        User user = new User();
        user = modelMapper.map(userLocationDTO, User.class);
        return user;
    }

Here is the complete code:

    private UserLocationDTO convertEntityToDto(User user){
        modelMapper.getConfiguration()
                .setMatchingStrategy(MatchingStrategies.LOOSE);
        UserLocationDTO userLocationDTO = new UserLocationDTO();
        userLocationDTO = modelMapper.map(user, UserLocationDTO.class);
        return userLocationDTO;
    }

    private User convertDtoToEntity(UserLocationDTO userLocationDTO){
        modelMapper.getConfiguration()
                .setMatchingStrategy(MatchingStrategies.LOOSE);
        User user = new User();
        user = modelMapper.map(userLocationDTO, User.class);
        return user;
    }

Run and Test Spring boot application

Just go to the root directory of the application and type the following command to run it -

$ mvn spring-boot:run

The application will start at Spring Boot’s default tomcat port 8080.

Hit below URL in browser to get response of the REST API:

http://localhost:8080/users-location

Conclusion

In this tutorial, we have seen how to use ModelMapper library to automatically convert Entity to DTO and vice-versa in Spring boot application.

The source code of this tutorial available on our GitHub repository at https://github.com/RameshMF/springboot-dto-tutorial