Question

我有Application实体，想在JPA中表达与属性的自我双向关系。 EX。 QuoteStore（提供商应用程序）为在线门户和许多（消费者应用程序）提供服务和QuoteStore（消费者应用程序）消耗来自Siebel CRM和许多（提供者应用程序）的服务当关系是ManyToMany而不是self（例如App2DB或App2BizCase）时，上述方法很有效对于自身双向ManyToMany与应用程序实体上的属性的关系;我将它分解为两个OneToMany关系，如

App 1--One2Many--* App2AppLink *--ManyToOne-1 App
(Provider 1--One2Many--* App2AppLink *--ManyToOne-1 Consumer)

这是Application Entity

@Entity
public class ApplicationEO {
  @Id
  @GeneratedValue(strategy = GenerationType.IDENTITY)
  private long id;

  /**
   * This application instance services are consumed by  Set<App2AppLinkEO> applications connections/links
   */
  @OneToMany(mappedBy = "provider")
  private Set<App2AppLinkEO> consumberLinks;

  /**
   * This application instance consumes services by Set<App2AppLinkEO> applications connections/links
   */
  @OneToMany(mappedBy = "consumer")
  private Set<App2AppLinkEO> providerLinks;

}

这是Application to Application关系表

@Entity
@Table(name="APP2APPLINK")
public class App2AppLinkEO {

  @EmbeddedId
  @AttributeOverrides({@AttributeOverride(name = "entity1Id", column = @Column(name = "PROVIDER_ID")),
      @AttributeOverride(name = "entity2Id", column = @Column(name = "CONSUMBER_ID"))})

  private CompositePK id;

  @ManyToOne(optional = false)
    private ApplicationEO providerApp;

  @ManyToOne(optional = false)
   private ApplicationEO consumerApp;

  private String service;

  private String status;

  private String platform;
}

这是复合主键代码

@Embeddable
public class CompositePK implements Serializable {

  private long entity1Id;

  private long entity2Id;
}

以上设置生成关系表：

CREATE TABLE APP2APPLINK (
                          PLATFORM VARCHAR(255), 
                          STATUS VARCHAR(255), 
                          SERVICE VARCHAR(255), 
                          PROVIDER_ID BIGINT NOT NULL, 
                          CONSUMBER_ID BIGINT NOT NULL, 
                          CONSUMERAPP_ID BIGINT, 
                          PROVIDERAPP_ID BIGINT, 
                          PRIMARY KEY (PROVIDER_ID, CONSUMBER_ID))

但为什么我会在下面看到额外的列？

 CONSUMERAPP_ID BIGINT, 
 PROVIDERAPP_ID BIGINT,

Answer 1

您没有在@ ManyToOne上设置@JoinColumn，因此他们获得默认的连接列名称。你需要给予，

@JoinColumn(name="PROVIDER_ID", insertable=false, updateable=false)

@JoinColumn(name="CONSUMBER_ID", insertable=false, updateable=false)

当您从EmbeddedId编写字段时，您需要将它们标记为只读（或者您可以将其标记为insertable = false，updateable = false）

但实际上你应该完全删除EmbeddedId并将@Id添加到@ ManyToOne并定义@IdClass。

Self ManyToMany使用JPA 2.0添加其他列

1 个答案: