Using Model Mapper in SpringBoot

What is Model Mapper?

Model Mapper is a java library used to map between the Entity object and DTO object.

Steps to do it:

1. Add the dependency in pom.xml

<!-- https://mvnrepository.com/artifact/org.modelmapper/modelmapper -->
<dependency>
    <groupId>org.modelmapper</groupId>
    <artifactId>modelmapper</artifactId>
    <version>3.2.0</version>
</dependency>

<dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-databind</artifactId>
</dependency>

2. Add ModelMapper Configuration, create new class in configuration package. Named it as ModelMapperConfiguration

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

3. Product Model Class and ProductRequest Class

@Data
@AllArgsConstructor
@NoArgsConstructor
@Entity
@Table(name = "products")
public class Product {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private int productId;

    private String description;

    @Column(nullable = false)
    @NotNull
    private double price;

    @Column(nullable = false)
    @NotNull
    private double stock;

    public Product(String description, double price, double stock) {
        this.description = description;
        this.price = price;
        this.stock = stock;
    }
}

@Data
@AllArgsConstructor  
@NoArgsConstructor
public class ProductRequest {
    private String description;

    @Column(nullable = false)
    @NotNull
    private double price;

    @Column(nullable = false)
    @NotNull
    private double stock;
}

4. Next we map between Model Class and DTO class in ProductServiceImp

@Service
@Log4j2
public class ProductServiceImp {

    private ProductRepository productRepository;
    private ModelMapper modelMapper;

    public ProductService(ProductRepository productRepository,
                          ModelMapper modelMapper) {
        this.productRepository = productRepository;
        this.modelMapper = modelMapper;
    }
    

    public Product addProduct(ProductRequest productRequest){

        // Map ProductRequest to Product using ModelMapper
        Product product = modelMapper.map(productRequest, Product.class);

        log.info("adding product");
        // Save the mapped Product to database
        return productRepository.save(product);
    }
}