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程序问答发布时间：2022-06-02 发布网站：大佬教程 code.js-code.com

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如何解决Jpa 无法将 json 映射到每次都重新创建的实体？

开发过程中遇到Jpa 无法将 json 映射到每次都重新创建的实体的问题如何解决？下面主要结合日常开发的经验，给出你关于Jpa 无法将 json 映射到每次都重新创建的实体的解决方法建议，希望对你解决Jpa 无法将 json 映射到每次都重新创建的实体有所启发或帮助；

我有一个包含 3 个实体的项目，如示例中所示：

1：

@Entity
@table(name = "GOAL")
@Getter
@Setter
@EqualsAndHashCode(onlyExplicitlyIncluded = truE)
public class GoalEntity implements Length {

    @ID
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @column(name = "GOAL_ID",nullable = false,updatable = truE)
    @EqualsAndHashCode.Include
    private Long ID;

    @column(name = "name",length = Name)
    private String name;

    @OnetoMany(mappedBy = "goal",fetch = FetchType.EAGER,cascade = CascadeType.ALL,orphanRemoval = truE)
    private List<GoalQuestionEntity> goalQuestions;

}

2：

@Entity
@table(name = "GOAL_QUESTION")
@Getter
@Setter
@EqualsAndHashCode(onlyExplicitlyIncluded = truE)
public class GoalQuestionEntity implements MprcMaxLength {

    @ID
    @GeneratedValue(strategy = GenerationType.IDENTITY)
//    @GeneratedValue(strategy = GenerationType.SEQUENCE)
    @column(name = "GOAL_QUESTION_ID",updatable = falsE)
    @EqualsAndHashCode.Include
    private Long ID;

    @column(name = "title",length = Name)
    private String title;

    @column(name = "DESCRIPTION",length = Name)
    private String description;

    @manyToOne(fetch = FetchType.EAGER)
    @Joincolumn(name = "GOAL_ID")
    private GoalEntity goal;

    @OnetoMany(mappedBy = "goalQuestion",orphanRemoval = truE)
    private List<GoalQuestionANSWEREntity> goalQuestionAnswers;

}

3：

@Entity
@table(name = "GOAL_QUESTION_ANSWER")
@Getter
@Setter
@EqualsAndHashCode(onlyExplicitlyIncluded = truE)
public class GoalQuestionANSWEREntity implements MprcMaxLength {

    @ID
    @GeneratedValue(strategy = GenerationType.SEQUENCE)
    @column(name = "GOAL_QUESTION_ANSWER_ID",updatable = falsE)
    @EqualsAndHashCode.Include
    private Long ID;

    @column(name = "TEXT",length = Name)
    private String text;

    @manyToOne(fetch = FetchType.EAGER)
    @Joincolumn(name = "GOAL_QUESTION_ID")
    private GoalQuestionEntity goalQuestion;

}

还有一个仓库：

@Repository
public interface GoalJpaRepository extends JpaRepository<GoalEntity,Long> {

}

现在，我想在每次传递整个数据结构时从前端调用 API：

[
  {
    "ID": 25,"name": "goal 1","goalQuestions": [
      {
        "ID": 21,"title": "title","description": "desc","goalQuestionAnswers": [{
          "ID": null,"text": "Hello"
        }
      ]
      }
    ]
  },{
    "ID": 26,"name": "goal 2","goalQuestions": null
  },{
    "ID": 27,"name": "goal 3","goalQuestions": null
  }
]

如果我传递空或不存在的实体 ID，我想创建一个新实体，如果 ID 已保存，我想更新实体。否则我想删除实体。可以用 jpa 做到这一点吗？

这是我正在使用的服务中的更新方法：

public List<GoalResponse> update(List<Goalrequest> goalrequestList) {
//        goalJpaRepository.deleteall();

        List<GoalEntity> goalEntityList = goalrequestList.stream().map(goalrequest -> {
            GoalEntity goalEntity = goalJpaRepository.findByID(goalrequest.getID()).orElse(new GoalEntity());
            questionsHelper.maprequestToEntity(goalrequest,goalEntity);
            return goalEntity;
        }).collect(Collectors.toList());

        goalEntityList = goalJpaRepository.saveAll(goalEntityList);

        return goalEntityList.stream().map(questionsHelper::mapEntityToResponsE).collect(Collectors.toList());
    }

这是映射方法：

public GoalEntity maprequestToEntity(Goalrequest goalrequest,GoalEntity goalEntity) {
        goalEntity.setID(goalrequest.getID());
        goalEntity.setname(goalrequest.getname());
        if (CollectionUtils.isnotEmpty(goalrequest.getGoalQuestions())) {
            if (goalEntity.getGoalQuestions() == null) {
                goalEntity.setGoalQuestions(new linkedList<>());
            }
            goalEntity.getGoalQuestions().clear();
            goalEntity.getGoalQuestions().addAll(mapGoalQuestionsrequestToEntity(goalrequest.getGoalQuestions(),goalEntity));
        }
        return goalEntity;
    }

private List<GoalQuestionEntity> mapGoalQuestionsrequestToEntity(List<GoalQuestionrequest> goalQuestionsrequests,GoalEntity goalEntity) {
        List<GoalQuestionEntity> goalQuestionEntitIEs = goalQuestionsrequests
                .stream()
                .map(goalQuestionrequest -> {
                    GoalQuestionEntity goalQuestionEntity = new GoalQuestionEntity();

                    goalQuestionEntity.setID(goalQuestionrequest.getID());
                    goalQuestionEntity.settitle(goalQuestionrequest.gettitle());
                    goalQuestionEntity.setDescription(goalQuestionrequest.getDescription());

                    goalQuestionEntity.setGoal(goalEntity);

                    if (CollectionUtils.isnotEmpty(goalQuestionrequest.getGoalQuestionAnswers())) {
                        if (goalQuestionEntity.getGoalQuestionAnswers() == null) {
                            goalQuestionEntity.setGoalQuestionAnswers(new linkedList<>());
                        }
                        goalQuestionEntity.getGoalQuestionAnswers().clear();
                        goalQuestionEntity.getGoalQuestionAnswers().addAll(mapGoalQuestionAnswerrequestToEntity(goalQuestionrequest.getGoalQuestionAnswers(),goalQuestionEntity));
                    }

                    return goalQuestionEntity;
                }).collect(Collectors.toList());
        return goalQuestionEntitIEs;
    }

private List<GoalQuestionANSWEREntity> mapGoalQuestionAnswerrequestToEntity(List<GoalQuestionAnswerrequest> goalQuestionAnswersrequests,GoalQuestionEntity goalQuestionEntity) {
        List<GoalQuestionANSWEREntity> goalQuestionAnswersEntitIEs = goalQuestionAnswersrequests
                .stream()
                .map(goalQuestionAnswerrequest -> {
                    GoalQuestionANSWEREntity goalQuestionANSWEREntity = new GoalQuestionANSWEREntity();
                    goalQuestionANSWEREntity.setID(goalQuestionAnswerrequest.getID());
                    goalQuestionANSWEREntity.setText(goalQuestionAnswerrequest.getText());

                    goalQuestionANSWEREntity.setGoalQuestion(goalQuestionEntity);

                    return goalQuestionANSWEREntity;
                })
                .collect(Collectors.toList());
        return goalQuestionAnswersEntitIEs;
    }