Hibernate 级联：对象引用未保存的瞬态实例 - 在刷新之前保存瞬态实例
@Entity
@Table(name = "parent")
public final class Parent extends Base {
@OneToOne(cascade = CascadeType.PERSIST, fetch = FetchType.EAGER)
private Person person;
并做（除其他外）：
Parent parent = new Parent();
Person person = new Person();
parent.setPerson(person);
session.save(parent);
我得到了提到的例外？
我之前需要手动调用 session.save(person) 吗？我是否必须向子类定义（引用父类的位置）添加级联类型注释？
或者我错过了其他明显的事情？
我不想使用 CascadeType.ALL 因为当删除父级时我想保留该人（子级）。
两个实体/表都扩展了一个公共基表：
@MappedSuperclass()
public abstract class Base {
@Id
@GeneratedValue(strategy=GenerationType.AUTO)
private Integer id;
public Integer getId() {
return id;
}
这会影响所需的级联类型吗？
@Entity
@Table(name = "parent")
public final class Parent extends Base {
@OneToOne(cascade = CascadeType.PERSIST, fetch = FetchType.EAGER)
private Person person;
and doing (amongst other things) this :
Parent parent = new Parent();
Person person = new Person();
parent.setPerson(person);
session.save(parent);
I get the mentioned exception ?
Do I manually need to call session.save(person) before ? do I have to add a cascade type annotation to the childs class definition(where it references the parent) ?
Or have I missed something else obvious ?
I don't want to use CascadeType.ALL as when a parent is deleted I want to keep the person(child).
Both entities/tables extend a common Base table :
@MappedSuperclass()
public abstract class Base {
@Id
@GeneratedValue(strategy=GenerationType.AUTO)
private Integer id;
public Integer getId() {
return id;
}
Will this effect which cascade type is required ?
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您没有提到 Hibernate 版本，但自从我开始使用它以来，这一点没有改变。
正如您可以在 Hibernate 参考，要获得 Java 标准
SAVE_UPDATE，您需要在 Hibernate 中使用{CascadeType.PERSIST, CascadeType.MERGE}。编辑：查看更新的信息，您现在所做的操作会导致 Hibernate 将其视为双向一对一映射。这基本上意味着，对于这两个表中任何一个中的每个对象，必须在另一个表中具有相同 ID 的对应对象。因此，您不能只删除其中之一，否则您将失去 FK 完整性。
如果您希望它是单向映射，例如，如果您希望能够删除该人但保留父级 - 您必须指定一个 FK，通常通过
@JoinColumn，例如@JoinColumn(name="PERSON_ID", unique=false, nullable=true, insertable=true, updatetable=true)You haven't mentioned the Hibernate version, but this hasn't changed since I ever started using it.
As you can read in the Hibernate reference, to get the Java standard
SAVE_UPDATEyou need{CascadeType.PERSIST, CascadeType.MERGE}in Hibernate.EDIT: Seeing the updated info, what you're doing now causes Hibernate to treat it as a bi-directional one-to-one mapping. This basically means that for each object in any of those two tables, there has got to be a counterpart in the other table with the same ID. Therefore, you cannot delete only one of them, you would lose FK integrity.
If you want it to be a unidirectional mapping, e.g., if you want to be able to delete the person but leave the parent -- you have to specify a FK, usually via
@JoinColumn, like@JoinColumn(name="PERSON_ID", unique=false, nullable=true, insertable=true, updatable=true)