Introduction

Spring Boot and ModelMapper is a powerful combination for simplifying the mapping of data between entities and DTOs (Data Transfer Objects) in Java applications. This guide provides an introduction to integrating Spring Boot with ModelMapper, explains the benefits of ModelMapper, and offers sample code with explanations for its implementation.

Why Use ModelMapper with Spring Boot?

ModelMapper is a popular Java library that simplifies the conversion and mapping of objects. When integrated with Spring Boot, it offers several advantages:

• Simplified Mapping: ModelMapper automates the mapping of fields between entities and DTOs, reducing the need for manual mapping code.
• Enhanced Productivity: By eliminating repetitive mapping code, ModelMapper allows developers to focus on the core logic of their application.
• Customizable Mappings: ModelMapper provides flexibility to configure custom mappings and control how data is transferred between objects.

Getting Started with Spring Boot and ModelMapper

To start simplifying object mapping with Spring Boot and ModelMapper, follow these steps:

1. Create a Spring Boot project using the Spring Initializr or your preferred IDE.
2. Add the ModelMapper dependency to your project's pom.xml (Maven) or build.gradle (Gradle) file:

<!-- Maven -->
<dependency>
    <groupId>org.modelmapper</groupId>
    <artifactId>modelmapper</artifactId>
</dependency>
        

// Gradle
dependencies {
    implementation 'org.modelmapper:modelmapper:2.3.5'
}
        

3. Create your entity and DTO classes, and define the mapping configuration using ModelMapper:

import org.modelmapper.ModelMapper;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
@Service
public class UserService {
    private final UserRepository userRepository;
    private final ModelMapper modelMapper;
    @Autowired
    public UserService(UserRepository userRepository, ModelMapper modelMapper) {
        this.userRepository = userRepository;
        this.modelMapper = modelMapper;
    }
    public UserDto getUserById(Long userId) {
        User user = userRepository.findById(userId)
                .orElseThrow(() -> new EntityNotFoundException("User not found"));
        return modelMapper.map(user, UserDto.class);
    }
}
        

4. ModelMapper will handle the mapping of fields between the entity and DTO, simplifying the process:

@Entity
public class User {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    private String username;
    private String email;
    // Other fields and getters/setters
}
        

public class UserDto {
    private Long id;
    private String username;
    // Other fields and getters/setters
}
        

Conclusion

Spring Boot and ModelMapper is a valuable combination for simplifying the mapping of data between entities and DTOs in your Java applications. This guide introduced the integration, explained the benefits of ModelMapper, and provided sample code for creating DTOs, entities, and mapping logic. As you explore this combination further, you'll find it valuable for maintaining clean and efficient object mapping in your Spring Boot projects.