Conversion of DTO to entity and vice-versa

Question

I am using Spring MVC architecture with JPA in my web application. Where to convert data transfer object (DTO) to JPA entity and vice-versa, manua

Answer 1

I can recommend to use mapstruct library:

    org.mapstruct
    mapstruct-jdk8
    1.2.0.Final

For example, if you have such an entity:

public class Entity {
    private Integer status;
    private String someString;
    private Date startDate;
    private Date endDate;

    // SKIPPED

And DTO:

public class Dto {
    private Boolean status;
    private String someString;
    private Long startDate;
    private Long endDate;

    // SKIPPED

Then the transformation can be done in the service layer by this way:

@Service
public class SomeServiceImpl implements SomeService {

    @Autowired
    SomeDao someDao;

    @Autowired
    SomeMapper someMapper;


    public Dto getSomething(SomeRequest request) throws SomeException {
        return someDao.getSomething(request.getSomeData())
                .map(SomeMapper::mapEntityToDto)
                .orElseThrow(() -> new SomeException("..."));
    }

Mapper can be represented as follows:

@Mapper 
public interface SomeMapper {
    @Mappings(
            {@Mapping(target = "entity", 
                      expression = "java(entity.getStatus() == 1 ? Boolean.TRUE : Boolean.FALSE)"),
             @Mapping(target = "endDate", source = "endDate"),
             @Mapping(target = "startDate", source = "startDate")
            })

    Dto mapEntityToDto(Entity entity);
}