Convert an object attribute to mapstruct - spring-boot

Question

My DTO:
public class ObjectDTO implements Serializable {
private Long id;
private String title;
private Long parentId;
...
}
My Entity:
public class MyObject implements Serializable {
private static final long serialVersionUID = 1L;
#Id
#GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "sequenceGenerator")
#SequenceGenerator(name = "sequenceGenerator")
#Column(name = "id")
private Long id;
#Column(name = "title")
private String title;
#Column(name = "parent_id")
#ManyToOne
private MyObject parent;
....
}
My Mapper:
#Mapper(componentModel = "spring")
public interface ObjectMapper extends EntityMapper<ObjectDTO, MyObject> {
#Mapping(target = "parentId", source = "m.parent.id")
ObjectDTO toDto(MyObject m);
}
Exception:
error: Can't map property "Long parentId" to "MyObject parentId". Consider to declare/implement a mapping method: "MyObject map(Long value)". Occured at 'E toEntity(D dto)' in 'EntityMapper'.
Please tell me what is the reason, and what are the correct actions when extracting the attribute
UPDATE:
This is my interface for Mapper
public interface EntityMapper<D, E> {
E toEntity(D dto);
D toDto(E entity);
}

Answer 1

just do what mapstruct is telling you to do: you are missing a method with signature MyObject map(Long value) needed by autogenerated toEntity() method for property mapping ObjectDTO.parentId mapped to MyObject.parent.
Check MapStruct Object factories; them may be the right way to solve your problem.