将AbstractEntity映射到SubClassDTO-单表策略

Question

我正在尝试将Entity（TrainingEntity）映射到DTO，其中的一个字段是Set with ManyToMany引用一个AbstractEntity（CoachEntity）的集合，该集合被Single Table分为两个子类：ExternalCoach和InternalCoach。

两个子类都有不同的数据，因此需要两个不同的映射器。

@Entity
@Table(name = "TRAINING")
public class TrainingEntity extends AbstractEntity {

    @ManyToMany()
    @JoinTable(name = "TRAINING_EMPLOYEE", joinColumns = { @JoinColumn(name = "TRAINING_ID") }, inverseJoinColumns = {
            @JoinColumn(name = "COACH_ID") })
    private Set<CoachEntity> coachEntities;

@Column(nullable = false)
private TrainingType trainingType;

......some data....

}

抽象教练实体

    @Entity
    @Table(name = "COACH")
    @DiscriminatorColumn(name = "TYPE", discriminatorType = DiscriminatorType.STRING)
    @Inheritance(strategy = InheritanceType.SINGLE_TABLE)
    public abstract class CoachEntity extends AbstractEntity {

 ......some data....

}

教练子类：

@Entity
@DiscriminatorValue("EXTERNAL")
public class ExternalCoachEntity extends CoachEntity {
 ......some data....
}



@Entity
@DiscriminatorValue("INTERNAL")
public class InternalCoachEntity extends CoachEntity {
 ......some data....
    }

一个用于Abstract Coach类的映射器将无法访问方法和字段的子类，因此对于External和Internal，我需要两个映射器。比我不得不在TrainingMapper类中使用它们，但是（内部示例）：

public class CustomTrainingMapper {

    public static TrainingDto toTrainingDto(TrainingEntity trainingEntity){
        if(trainingEntity == null){
            return null;
        }

        if(trainingEntity.getTrainingType().equals(TrainingType.INTERNAL)){
            Set<CoachEntity> coachEntities = trainingEntity.getCoachEntities();


            Set<CoachDto> coachDtos = CustomInternalCoachMapper.toDTOSet((Set<InternalCoachEntity>)coachEntities);
        }

我得到：

  cannot cast from Set<CoachEntity> to Set<InternalCoachEntity>

不进行强制转换，根本看不到带有子类输入的映射器方法。

The method toDTOSet(Set<InternalCoachEntity>) in the type CustomInternalCoachMapper is not applicable for the arguments (Set<CoachEntity>)

在mapper中，我将方法输入更改为抽象Coach类时，看不到子类的方法和字段。

InternalMapper的一部分：

public class CustomInternalCoachMapper {

    public static CoachDto toCoachDto(InternalCoachEntity coachEntity) {
        if (coachEntity == null) {
            return null;
        }

        EmployeeDto employeeDto = CustomEmployeeMapper.toEmployeeDto(coachEntity.getEmployeeEntity());

        return new InternalCoachDto(coachEntity.getId(), coachEntity.getVersion(), coachEntity.getCreateDate(),
                coachEntity.getUpdateDate(), coachEntity.getName(), coachEntity.getSurname(), employeeDto);
    }

是否可以将此AbstractEntity Set映射到子类DTO中？ 我也尝试过使用AbstractDto for Coachs，但是后来我遇到了同样的问题，无法访问子类的getter和setter。