具有层次关系的 JPA 实体

Question

我有以下实体

@Entity 
public class Project implements Serializable { 
    @Id
    private Integer project_id;
    private String project_name;
    other attributes

    @OneToOne
    @JoinColumn(name = "lead_emp_no", referencedColumnName = "emp_no")
    private Employee projectLead;

    //  but the following two relationships need to be a connect by:
    @OneToOne
    @JoinColumn(name = "lead_boss_emp_no", referencedColumnName = "emp_no")
    private Employee projectLeadBoss;

    @OneToOne
    @JoinColumn(name = "lead_bosses_boss_emp_no", referencedColumnName = "emp_no")
    private Employee projectLeadBossesBoss;

使用此设置，我们必须手动维护 Lead 的上司和 Lead 的上司的上司的员工编号。了解 projectLead 员工后，这种关系 [在某种程度上] 已经可用：

员工实体如下：

  @Entity
  public class Employee implements Serializable {
  @Id
  private Integer emp_no;
  private Integer bosses_emp_no;

是否可以让我的 Project 实体基于 ​​projectLead 连接到老板和老板 Employee？在单个查询中，我想获得所有项目及其领导层级的表。我对实体重新设计持开放态度。

Answer 1

您可以将Employee 中的bosses_emp_no 替换为更有用的boss：

@Entity
public class Employee implements Serializable {

    @Id
    private Integer emp_no;

    @OneToOne
    @JoinColumn(name = "boss_emp_no", referencedColumnName = "emp_no")
    private Employee boss;

然后你只需向Project添加几个委托方法

public Employee getProjectLeadBoss() {
    return this.projectLead.getBoss();
}

public Employee getProjectLeadBossesBoss() {
    return this.getProjectLeadBoss().getBoss();
}