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[英]How to prevent update operation only in child table in hibernate (one-to-many mapping unidirectional)?
[英]Unidirectional one-to-many mapping in Hibernate generates redundant updates
我定義了兩個類,Parent和Child。 父母可以有一個孩子的列表。
@Entity
public class Parent {
@Id
@GeneratedValue(...)
@SequenceGenerator(...)
private long id;
@OneToMany(fetch = FetchType.EAGER, cascade = CascadeType.ALL)
@JoinColumn(name = "parent_id", referencedColumnName = "id", nullable = false)
private List<Child> children;
public Parent() {
children = new ArrayList<Child>();
}
public void addChild(Child child) { children.add(child); }
}
@Entity
public class Child {
@Id
@GeneratedValue(...)
@SequenceGenerator(...)
private long id;
// The "Child" table in the db also has a not-null "parent_id" column.
}
如果我將一堆子項添加到列表中並保持父項一切正常工作:Hibernate獲取序列值,存儲父項,然后存儲所有子項。
但是,完成所有這些操作后,它會更新所有子項,將“parent_id”設置為插入中已設置的值!
生成的SQL如下所示:
insert into PARENT (id) values (1)
insert into CHILD (parent_id, id) values (1, 1)
insert into CHILD (parent_id, id) values (1, 2)
insert into CHILD (parent_id, id) values (1, 3)
update CHILD set parent_id = 1 WHERE id = 1
update CHILD set parent_id = 1 WHERE id = 2
update CHILD set parent_id = 1 WHERE id = 3
如果我使這個關聯雙向,它工作正常,但然后我需要在我的子類中引用父,這是我想要避免的。
存儲庫是Spring Data JPA存儲庫:
public interface ParentRepository extends PagingAndSortingRepository<Parent, Long> {}
創建和保存對象的(簡化)代碼:
Parent parent = new Parent();
parent.addChild(new Child());
parent.addChild(new Child());
repo.save(parent);
有什么建議么?
你有沒有嘗試過:
@JoinColumn(name = "parent_id", referencedColumnName = "id", nullable = false, insertable=false, updatable=false)
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