生成的复合 PK null id

Question

Spring Boot：2.0.2

休眠核心：5.2.17

方言：SQLServer2012方言

当尝试使用 JpaRepository save() 方法保存 DistributionActivities 实体时，操作失败并显示以下消息：

org.hibernate.id.IdentifierGenerationException: null id 生成 for：类 DistributionActivityEmails

父实体：

@Entity
@Table(name = "DistributionActivities")
public class DistributionActivities implements Serializable 
{   
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)    
    @Column(name ="ActivityID")
    private Long activityID;

    @OneToMany(cascade={CascadeType.ALL})
    @Fetch(FetchMode.JOIN)
    @JoinColumn(name="activityID", referencedColumnName="activityID")
    private Set<DistributionActivitiesEmails> distributionActivitiesEmails;
}

子实体：

@Entity
@Table(name = "DistributionActivitiesEmails ")
public class DistributionActivitiesEmails implements Serializable 
{
    @EmbeddedId
    private DistributionActivitiesEmailsId id;

    @Length(max = 50)
    private String EmailAdress;
}

复合PK：

@Embeddable
public class DistributionActivitiesEmailsId implements Serializable 
{
    @ManyToOne
    @JoinColumn(name="ActivityID")
    private DistributionActivities distributionActivities;

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)    
    @Column(name ="ActivityEmailID")
    private Long activityEmailID;    
} 

Answer 1

根据@EmbeddedId javadoc，不支持在嵌入式 id 类中定义的关系映射。