Oracle分层数据的JPA/Hibernate map@OneTomany

Question

id name parent_id
1  A    1
2  A1   1
3  A2   1
4  A11  2

select * from Organization start with id=1 connect by nocycle prior id=parent_id;

with o_hier as (select o.id, o.parent_id, CONNECT_BY_ISCYCLE as lvl from Organization o start with id=4 connect by nocycle prior parent_id = id) select o.* from Organization o, o_hier where o.id = o_hier.id union all select o.* from Organization o, o_hier where o.id = o_hier.parent_id and o_hier.lvl = 1;

@Entity
@Table(name = "Organization")
public class OrganizationEntity {

    //getter/setter omitted for readability

    @Id
    @Column(name = "ID")
    private String id;

    @Column(name = "NAME")
    private String name;

    @ManyToOne(fetch = FetchType.LAZY)
    @???
    List<OrganizationEntity> descendants = new ArrayList<>();

    @ManyToOne(fetch = FetchType.LAZY)
    @???
    List<OrganizationEntity> ancestors= new ArrayList<>();
}

我知道可能的性能问题，但是我们可以使用Hibernate/JPA映射类似的东西吗？

Answer 1

这是一个棘手的问题。您可以使用标准的父映射和子映射。

@ManyToOne(fetch = FetchType.LAZY)
@JoinColumn(name = "ID")
OrganizationEntity parent;

@OneToMany(fetch = FetchType.LAZY)
@mappedBy(mappedBy="parent")
List<OrganizationEntity> childern;

然后使用标准的tree taversals算法得到所有的祖先（简单while循环）或所有的后代（一些DFS变体，通常是预先排序）。

治疗方面，这个伤口很慢。