Java JPA-ManyToOne-JoinTable-无法更新字段

我有以下情况：

anagraficaiscriti.java

@Entity
@Table(name="ANAGRAFICA_ISCRITTI")
public class AnagraficaIscritti implements Serializable {
        private static final long serialVersionUID = 1L;

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name="ID_EMAIL",insertable=false, updatable=false)
    private long idEmail;

    private String email;

    //bi-directional many-to-many association to Newsletter 
    @ManyToMany(mappedBy="anagraficaIscrittis")
    private List<Newsletter> newsletters;

    //bi-directional many-to-one association to IscrizioniEmail
    @OneToMany(mappedBy="anagraficaIscritti")
    private List<IscrizioniEmail> iscrizioniEmails;

IscrizioniEmailPK.java

@Embeddable
public class IscrizioniEmailPK implements Serializable {
        //default serial version id, required for serializable classes.
        private static final long serialVersionUID = 1L;

        @Column(name="ID_EMAIL", insertable=false, updatable=false)
        private long idEmail;

        @Column(name="ID_NEWSLETTER", insertable=false, updatable=false)
        private long idNewsletter;

当我试图创建一个对象anagraficaiscriti和一个对象时事通讯时，一条记录也会自动插入到IscrizioniEmail中。例如，我创建：

 ANAGRAFICA_ISCRITTI
 ID_EMAIL           EMAIL
  1           john.doe@gmail.com

 NEWSLETTER
 ID_NEWSLETTER      NEWSLETTER
      1               sport

 ISCRIZIONI_EMAIL
  ID_EMAIL   ID_NEWSLETTER   SUBSCRIPTION_DATE
     1             1               NULL

---

但是，更新订阅日期（使用当前时间戳）的正确方法是什么，它是空的？如果我尝试创建一个对象IscrizioniEmail，我会得到重复的键错误等等。

您可以在

ISCRIZIONI\u EMAIL

表中为

SUBSCRIPTION\u DATE

设置默认值，该值将是当前日期。这样您就不需要从Java发送它了

---

如果您需要从Java发送该值，那么您可以在插入

Newsletter

和

anagraficaiscriti

表之后，使用

IscrizioniEmail

实体类执行更新查询。

您是否尝试过创建

@entity

实体类

IscrizioniEmail

？我不明白。实体类IscrizioniEmail存在。谢谢，定义默认值很有效：

SUBSCRIPTION\u DATE

DATETIME default NOW（）我认为JPA有时非常复杂。

@Embeddable
public class IscrizioniEmailPK implements Serializable {
        //default serial version id, required for serializable classes.
        private static final long serialVersionUID = 1L;

        @Column(name="ID_EMAIL", insertable=false, updatable=false)
        private long idEmail;

        @Column(name="ID_NEWSLETTER", insertable=false, updatable=false)
        private long idNewsletter;

 ANAGRAFICA_ISCRITTI
 ID_EMAIL           EMAIL
  1           john.doe@gmail.com

 NEWSLETTER
 ID_NEWSLETTER      NEWSLETTER
      1               sport

 ISCRIZIONI_EMAIL
  ID_EMAIL   ID_NEWSLETTER   SUBSCRIPTION_DATE
     1             1               NULL