java - 如何在 JPA Hibernate 中对外部列进行排序？

Question

我有一个名为 Project 的实体，其中包含一个具有 name 字段的外部 Department 实体(见下文):

@Entity
@Table(name = "project")
public class Project 
{
  @GeneratedValue(generator = "system-uuid")
  @GenericGenerator(name = "system-uuid", strategy = "uuid2")
  @Type(type = "pg-uuid")
  @Id
  @Column(name = "project_id")
  private UUID id;

  @Column(nullable = false)
  private String name;

  @Column(nullable = true, unique = false)
  private String description;

  @ManyToOne(fetch = FetchType.LAZY)
  @JoinColumn(name = "department_id", nullable = false)
  private Department department;

  ...
}

然后，在我的 ProjectService 类中，我有一个方法:

    public Page<Project> findByFilterSort(final ProjectSearchDTO dto,
                                          ProjectSortBy sortBy,
                                          Direction direction,
                                          int pageNumber,
                                          int pageSize)
    {
        BooleanBuilder builder = createFilter(dto);

        Sort sort;
        switch (sortBy)
        {
            case NAME:
                sort = new Sort(new Order(direction, "name"),
                                new Order(Direction.DESC, "created"));
                break;
            case DEPARTMENT_NAME:
                ???

            ...
        }

        PageRequest request = new PageRequest(pageNumber-1, pageSize, sort);

        return projectRepository.findAll(builder, request);
    }

有没有办法使用这种方法按name对Department进行排序？如果是，怎么办？如果没有，最好的方法是什么？

提前致谢。

Answer 1

已解决:

我应该尝试一下。就像使用点 (.) 运算符引用字段一样简单。哇。

case DEPARTMENT_NAME:
       sort = new Sort(new Order(direction, "department.name"),
                       new Order(Direction.DESC, "created"));