Spring jpa存储库返回实体类而不是dto接口

Question

我在后端代码中使用了Spring数据jpa。我已经包含了实体，dto接口，服务和jpa存储库代码。

现在的问题是，当我在< code>TopicService中调用< code>getAllTopics()时。它返回< code>Topic对象的列表，而不是< code>TopicDto。< code>Topic对象包含一个< code >示例列表，我没有将它包含在< code>TopicDto中。并且< code>Topic对象还包括一个< code>Comment对象列表，而不是< code > Comment tdo 。

这仅在我添加Set时发生

@Entity
@Table(name = "TOPIC")
@Data
@NoArgsConstructor
@AllArgsConstructor
public class Topic implements Serializable {

    @Id
    @GeneratedValue(strategy=GenerationType.IDENTITY)
    private Long id;

    @OneToMany(
            fetch = FetchType.LAZY, 
            cascade = CascadeType.REMOVE,
            mappedBy = "topic"
        )
    private Set<Comment> comments= new HashSet<>();

    @OneToMany(
            fetch = FetchType.LAZY, 
            cascade = CascadeType.REMOVE,
            mappedBy = "topic"
        )
    private Set<Example> examples = new HashSet<>();

}

@Entity
@Table(name = "COMMENT")
@Data
@NoArgsConstructor
@AllArgsConstructor
public class Comment implements Serializable {
    
    @Id
    @GeneratedValue(strategy=GenerationType.IDENTITY)
    private Long id;
        
    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "Topic_ID")
    private Topic topic;

    @OneToMany(
            fetch = FetchType.LAZY, 
            cascade = CascadeType.REMOVE,
            mappedBy = "comment"
        )
    private Set<AnotherExample> anotherExamples = new HashSet<>();  
}

public interface TopicDto{
    Long getId();
    Set<CommentDto> getComments();
}

public interface CommentDto{
    Long getId();
}

public interface TopicRepository extends JpaRepository<Topic, Long> {   
    List<TopicDto> findAllBy(Sort sort);
}

@Service
@Transactional
public class TopicService {
   private final TopicRepository topicRepository ;

   public TopicService(TopicRepository topicRepository ) {
      this.topicRepository = topicRepository ;
   }

   @Transactional(readOnly = true)
   public List<TopicDto> getAllTopics(Sort sort) {
      List<TopicDto> l = topicRepository.findAllBy(sort);
      return l;
   } 
}




Answer 1

–存储库管理的域类型–存储库所管理的实体的id类型

所以返回域对象是正常的。您指定了@Entity主题类。

我希望答案是有帮助的。

Answer 2

首先，将您的TopicRepository更改为使用主题Topic，而不是

public interface TopicRepository extends JpaRepository<Topic, Long> {   
    List<Topic> findAllBy(Sort sort);
}

然后，您需要以下 DTO 类：

import java.util.HashSet;
import java.util.Set;

public class TopicDto {
    private Long id;
    private Set<CommentDto> comments= new HashSet<>();

    public TopicDto(Long id, Set<CommentDto> comments) {
        this.id = id;
        this.comments = comments;
    }
}

public class CommentDto {
    private Long id;

    public CommentDto(Long id) {
        this.id = id;
    }
}

最后，在您的TopicService中，您需要执行从Topic到TopicDto的映射，如下所示：

@Service
@Transactional
public class TopicService {
   private final TopicRepository topicRepository ;

   public TopicService(TopicRepository topicRepository ) {
      this.topicRepository = topicRepository ;
   }

   @Transactional(readOnly = true)
   public List<TopicDto> getAllTopics(Sort sort) {
      List<Topic> topics = topicRepository.findAllBy(sort);
      return topics.stream()
                .map(topic -> {
                    Set<CommentDto> commentsDto = topic.getComments().stream()
                            .map(comment -> new CommentDto(comment.getId()))
                            .collect(Collectors.toSet());
                    return new TopicDto(topic.getId(), commentsDto);
                })
                .collect(Collectors.toList());
   } 
}