如何让 Hibernate 在合并时忽略 @OneToMany？

Question

public class Application{
   @Id
   private Long id;

   @OneToMany(mappedBy = "application")
   private List<Licence> licences = new ArrayList<Licence>();
   ...
}

public class Licence{
   @Id
   private Long id;

   @ManyToOne(fetch = FetchType.LAZY)
   @JoinColumn(name = "ID", nullable = false)
   private Application application;
   ...
}

当我去 em.merge(application); 时，如何让 hibernate 将许可证保留在应用程序对象中，而不是尝试保留许可证；

我不是要在应用程序中使用级联保存许可证。许可证在真正持久化之前有很多业务规则要运行，因此我将分别调用每个许可证的persist。我该怎么做呢 ？这适用于持久化，但不适用于合并。

在合并我不断得到

org.hibernate.TransientObjectException: object is an unsaved transient 
     instance - save the transient instance before merging: com.cmr.Licence

Answer 1

使用insertable = false, updatable = false. 更新这个

  @ManyToOne(fetch = FetchType.LAZY)
  @JoinColumn(name = "ID", nullable = false)
  private Application application;

到

  @ManyToOne(fetch = FetchType.LAZY)
  @JoinColumn(name = "ID", nullable = false, insertable = false, updatable = false)
  private Application application;