Spring Boot ModelMapper Example - Map Entity to DTO

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In a previous couple of tutorials, we created a Spring boot project and Built CRUD Restful web services with DTO.

Refer to previous tutorials:

Spring Boot 3 CRUD RESTful WebServices with MySQL Database

Spring Boot DTO Example Tutorial

In this tutorial, we will learn how to use the ModelMapper library to map the JPA entity into DTO and vice versa.

ModelMapper Library Overview

ModelMapper is a lightweight Java library used for object mappings.

The goal of ModelMapper is to make object mapping easy, by automatically determining how one object model maps to another, based on conventions, in the same way, that a human would - while providing a simple, refactoring-safe API for handling specific use cases.

Read more about ModelMapper at the official website: http://modelmapper.org/getting-started/

Prerequisites

This tutorial is a continuation of below two tutorials so first, create CRUD REST APIs using below tutorials:

Spring Boot 3 CRUD RESTful WebServices with MySQL Database

Spring Boot DTO Example Tutorial

Check out the complete source code of this tutorial is available on my GitHub repository at Spring Boot CRUD RESTful WebServices

Development Steps

1. Add Maven Dependency

2. Configure ModelMapper class a Spring Bean

3. Inject and Use ModelMapper Spring Bean in Service Class

4. Test CRUD REST APIs using Postman client

1. Add Maven Dependency

Open the 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>3.1.0</version>
		</dependency>

2. Configure ModelMapper class a Spring Bean

Next, let's configure ModelMapper class as Spring bean in the main entry point class of the Spring Boot application:

package net.javaguides.springboot;

import org.modelmapper.ModelMapper;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.Bean;

@SpringBootApplication
public class SpringbootRestfulWebservicesApplication {

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

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

}

We have configured ModelMapper as Spring bean using Java-based configuration:

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

3. Inject and Use ModelMapper Spring Bean in Service Class

Next, let's inject ModelMapper Spring bean in UserServieImpl class and use it's methods to convert the User JPA entity into UserDto and vice versa:

package net.javaguides.springboot.service.impl;

import lombok.AllArgsConstructor;
import net.javaguides.springboot.dto.UserDto;
import net.javaguides.springboot.entity.User;
import net.javaguides.springboot.exception.EmailAlreadyExistsException;
import net.javaguides.springboot.exception.ResourceNotFoundException;
import net.javaguides.springboot.mapper.UserMapper;
import net.javaguides.springboot.repository.UserRepository;
import net.javaguides.springboot.service.UserService;
import org.apache.logging.log4j.util.Strings;
import org.modelmapper.ModelMapper;
import org.springframework.stereotype.Service;
import org.springframework.util.StringUtils;

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

@Service
@AllArgsConstructor
public class UserServiceImpl implements UserService {

    private UserRepository userRepository;

    private ModelMapper modelMapper;

    @Override
    public UserDto createUser(UserDto userDto) {

        // Convert UserDto into User JPA Entity
       // User user = UserMapper.mapToUser(userDto);

        User user = modelMapper.map(userDto, User.class);

        User savedUser = userRepository.save(user);

        // Convert User JPA entity to UserDto
        //UserDto savedUserDto = UserMapper.mapToUserDto(savedUser);

        UserDto savedUserDto = modelMapper.map(savedUser, UserDto.class);

        return savedUserDto;
    }

    @Override
    public UserDto getUserById(Long userId) {
        User user = userRepository.findById(userId).get();
        //return UserMapper.mapToUserDto(user);
        return modelMapper.map(user, UserDto.class);
    }

    @Override
    public List<UserDto> getAllUsers() {
        List<User> users = userRepository.findAll();
//        return users.stream().map(UserMapper::mapToUserDto)
//                .collect(Collectors.toList());

        return users.stream().map((user) -> modelMapper.map(user, UserDto.class))
                .collect(Collectors.toList());
    }

    @Override
    public UserDto updateUser(UserDto user) {

        User existingUser = userRepository.findById(user.getId()).get();
        existingUser.setFirstName(user.getFirstName());
        existingUser.setLastName(user.getLastName());
        existingUser.setEmail(user.getEmail());
        User updatedUser = userRepository.save(existingUser);
        //return UserMapper.mapToUserDto(updatedUser);
        //return modelMapper.map(updatedUser, UserDto.class);
    }

    @Override
    public void deleteUser(Long userId) {
        userRepository.deleteById(userId);
    }
}

That's it. Next, let's run the Spring boot application and test all the CRUD REST APIs.

4. Test CRUD REST APIs using Postman Client

Create User REST API:

Request URL: http://localhost:8080/api/users

HTTP Method: POST
Request Body:

{
    "firstName": "ramesh",
    "lastName":"fadatare",
    "email": "ramesh@gmail.com"
}

Refer to this screenshot to test Create User REST API:

Get User REST API:

Request URL: http://localhost:8080/api/users/1

HTTP Method: GET

Refer to this screenshot to test GET User REST API:

Update User REST API:

Request URL: http://localhost:8080/api/users/1

HTTP Method: PUT
Request Body:

{
    "firstName": "ram",
    "lastName":"fadatare",
    "email": "ram@gmail.com"
}

Refer to this screenshot to test the Update User REST API:

Get All Users REST API:

Request URL: http://localhost:8080/api/users

HTTP Method: GET

Refer to this screenshot to test GET All User REST API:

DELETE User REST API:

Request URL: http://localhost:8080/api/users/1

HTTP Method: DELETE

Refer to this screenshot to test Delete User REST API:

Source Code on GitHub

The source code of this tutorial is available on my GitHub repository at Spring Boot CRUD RESTful WebServices

Conclusion

In this tutorial, we have seen how to use the ModelMapper library to convert JPA entity into DTO and vice versa in the Spring boot application.

Further Reading

• Spring Boot CRUD RESTful WebServices with MySQL Database
  
• Spring Boot DTO Example Tutorial
• Spring Boot ModelMapper Example
• Spring Boot MapStruct Example Tutorial

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