未生成 MapStruct 一对多关系

Question

I want to have a simple parent children relationship but somehow it does not work and I don't get what is missing.

Parent Mapper Interface (adding uses = {LayerMapper.class} does not change anything):

@Mapper(componentModel = "spring", unmappedTargetPolicy = ReportingPolicy.IGNORE)
@DecoratedWith(MlpConfigMapperDecorator.class)
public interface MlpConfigMapper {

    @Mapping(target = "epochNumber", source = "epochs")
    @Mapping(target = "activationFunction", ignore = true)
    MlpConfig toEntity(CustomMlpConfigRequest mlpConfigDto);
}

Parent decorator according to this answer ( https://stackoverflow.com/a/60217018/10565504 ):

public abstract class MlpConfigMapperDecorator implements MlpConfigMapper {

    @Autowired
    @Qualifier("delegate")
    private MlpConfigMapper delegate;

    @Autowired
    private ActivationFunctionService activationFunctionService;

    @Override
    public MlpConfig toEntity(CustomMlpConfigRequest mlpConfigDto) {

        MlpConfig mlpConfig = delegate.toEntity(mlpConfigDto);

        mlpConfig.setActivationFunction(activationFunctionService.findByType(mlpConfigDto.getActivationFunction()));

        return mlpConfig;
    }
}

The Parent DTO:

public class CustomMlpConfigRequest {

    private String name;

    private String description;

    private int batchSize;

    private int epochs;

    private List<LayerDto> layers;

    private String activationFunction;

}

The Child DTO:

public class LayerDto {

    public String type;
    public int orderNumber;
    public int neuronsNumber;

}

Parent Entity:

public class MlpConfig {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private long id;

    private String name;

    private String description;

    private int batchSize;

    private int epochNumber;

    @JoinColumn(nullable = false, name = "activationFunction_id")
    @ManyToOne(fetch = FetchType.LAZY)
    private ActivationFunction activationFunction;

    @JsonManagedReference
    @Column(nullable = false)
    @OneToMany(mappedBy = "mlpConfig", cascade = CascadeType.ALL)
    private List<Layer> layers;

    @ManyToOne(fetch = FetchType.LAZY)
    private User user;

    private Date lastUpdated;
}

Child Entity:

public class Layer {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private long id;

    private ELayer type;

    private int neuronsNumber;

    private int orderNumber;

    @EqualsAndHashCode.Exclude
    @ToString.Exclude
    @ManyToOne(fetch = FetchType.LAZY, optional=false)
    @JoinColumn(name = "mlpConfig_id", nullable=false)
    @JsonBackReference
    private MlpConfig mlpConfig;
}

Generated Child Entity Mapper Method (setChildren or setMlpConfig() in my case is missing):

@Override
public LayerDto layerToDto(Layer layer) {
    if ( layer == null ) {
        return null;
    }

    LayerDto layerDto = new LayerDto();

    if ( layer.getType() != null ) {
        layerDto.setType( layer.getType().name() );
    }
    layerDto.setOrderNumber( layer.getOrderNumber() );
    layerDto.setNeuronsNumber( layer.getNeuronsNumber() );

    return layerDto;
}

How do I get the mapper to set the parent in the child?

Answer 1

do you have Layer toEntity(LayerDto layerDto);

Also, on setter of layers on entity class, you should say, layers.forEach (layer -> layer.setmlpConfig(this));

Did you do that setting job? If you don't, layers of mplConfig entity can always be null when you try to get it.

Answer 2

In the end I fixed it myself. I don't know if it is best practice and probably the mapper should do it without manual help but at least it works:

public abstract class MlpConfigMapperDecorator implements MlpConfigMapper {

    @Autowired
    @Qualifier("delegate")
    private MlpConfigMapper delegate;

    @Autowired
    private ActivationFunctionService activationFunctionService;

    @Override
    public MlpConfig mlpConfigToEntity(CustomMlpConfigRequest mlpConfigDto) {

        MlpConfig mlpConfig = delegate.mlpConfigToEntity(mlpConfigDto);

        mlpConfig.setActivationFunction(activationFunctionService.findByType(mlpConfigDto.getActivationFunction()));
        
        //this is the difference. I set the config for the layer manually
        mlpConfig.getLayers().forEach(e -> e.setMlpConfig(mlpConfig));

        return mlpConfig;
    }
}