我试图持久化实体使用JPA。我有2个多对多关系的实体，我希望能够做双方的所有crud操作。

以下是我的表格示例：

@Entity
@Table(name = "workflow_tasks")
@Getter @Setter
@AllArgsConstructor @NoArgsConstructor
public class WorkflowTaskEntity {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    @Column(length = 30)
    private String workflowTaskId;

    @Column(unique = true)
    private String name;

    @ManyToMany(
        cascade = CascadeType.ALL,
        fetch = FetchType.EAGER
    )
    @JoinTable(
        name="workflow_tasks_workflow_tasks_settings",
        joinColumns = @JoinColumn(name = "workflow_task_id", referencedColumnName = "id"),
        inverseJoinColumns = @JoinColumn(name = "setting_id", referencedColumnName = "id")
    )
    private Set<WorkflowTaskSettingEntity> settings;
...
}

字符串

另一边：

@Entity
@Table(name = "workflow_task_settings")
@Getter @Setter
@AllArgsConstructor @NoArgsConstructor
public class WorkflowTaskSettingEntity {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    @Column(length = 30)
    private String workflowTaskSettingId;

    @Column(unique = true)
    private String name;

    @ManyToMany(
            cascade = CascadeType.ALL,
            mappedBy = "settings",
            fetch = FetchType.EAGER
    )
    private Set<WorkflowTaskEntity> workflowTasks;
}

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下面是一个实现的repository接口：

public interface WorkflowTaskSettingRepository
        extends CrudRepository<WorkflowTaskSettingEntity, Long> {
    Page<WorkflowTaskSettingEntity> findAll(Pageable pageRequest);
    List<WorkflowTaskSettingEntity> findAll();
    WorkflowTaskSettingEntity findByWorkflowTaskSettingId(String workflowTaskSettingId);

    WorkflowTaskSettingEntity findByValue(String name);

    @Modifying
    @Transactional
    @Query(value = "DELETE FROM WorkflowTaskSettingEntity c WHERE c.id = :id")
    void deleteById(@Param("id") Long id);
}

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以下是我必须处理的不同情况：

• 一次性创建WorkflowTaskSettingEntity和WorkflowTaskEntity对象
• 创建WorkflowTaskSettingEntity并将其链接到多个WorkflowTaskEntity对象
• 创建WorkflowTaskSettingEntity并将其链接到多个WorkflowTaskEntity
• 删除两个表之间的关系
• 删除工作流任务设置实体和关系
• 删除工作流任务实体和关系
  我创建条目时的第一个问题是我没有持久化所有关系：

我首先创造了：

• 4个WorkflowTaskEntity条目
• 我尝试持久化链接到我创建的4个条目的10个WorkflowTaskSettingEntity对象
• 第一个WorkflowTaskSettingEntity已正确持久化

的数据

**当持久化第二个对象时，它变得很奇怪：**理论上我应该有：

1-1, 1-2, 1-3, 1-4, 2-1, 2-2, 2-3, 2-4 ...

型
等等...但结果是这样的

的

**我的第二个问题涉及性能和代码长度：**我记录了我的SQL查询，并注意到对于基本的选择和插入有太多的SQL查询。我也想知道为什么我有分离实体的问题，并且必须持久化一个对象两次..
创建代码如下：

@Override
public WorkflowTaskSettingDto create(WorkflowTaskSettingDto workflowTaskSettingDto) {
    Set<WorkflowTaskDto> workflowTaskDtos = workflowTaskSettingDto.getWorkflowTasks();
    WorkflowTaskSettingEntity workflowTaskSettingEntity = modelMapper.map(
            workflowTaskSettingDto, WorkflowTaskSettingEntity.class);

    workflowTaskSettingEntity.setWorkflowTasks(null);
    workflowTaskSettingEntity = repository.save(workflowTaskSettingEntity);
    Set<WorkflowTaskEntity> workflowTaskEntities = getWorkflowTasks(workflowTaskDtos);
    workflowTaskSettingEntity.addWorkflowTasks(workflowTaskEntities);
    workflowTaskSettingEntity = repository.save(workflowTaskSettingEntity);

    return modelMapper.map(workflowTaskSettingEntity, WorkflowTaskSettingDto.class);
}

private Set<WorkflowTaskEntity> getWorkflowTasks(Set<WorkflowTaskDto> workflowTaskDtos) {
    Set<WorkflowTaskEntity> workflowTaskEntities = new HashSet<>();
    workflowTaskDtos.forEach(workflowTaskDto -> {
        WorkflowTaskEntity workflowTaskEntity =
                appService.workflowTaskService().getById(workflowTaskDto.getWorkflowTaskId());
        if (workflowTaskEntity == null) {
            WorkflowTaskDto create = appService.workflowTaskService().create(workflowTaskDto);
            workflowTaskEntity = appService.workflowTaskService().getById(create.getWorkflowTaskId());
        }
        workflowTaskEntity.setSettings(workflowTaskEntity.getSettings());
        workflowTaskEntities.add(workflowTaskEntity);
    });
    return workflowTaskEntities;
}

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