Java 生成";“关于删除级联”;使用Ebean
我使用的是Ebean,我需要最终将“on delete cascade”作为DDL(数据定义语言)——哪个注释会这样做?我试过了Java 生成";“关于删除级联”;使用Ebean,java,hibernate,orm,persistence,ebean,Java,Hibernate,Orm,Persistence,Ebean,我使用的是Ebean,我需要最终将“on delete cascade”作为DDL(数据定义语言)——哪个注释会这样做?我试过了 @OneToMany(cascade=CascadeType.REMOVE) 但这会给出“on delete restrict”/不会更改默认的“on delete restrict”?试试这个 @OneToMany(mappedBy = "parent", cascade = javax.persistence.CascadeType.REMOVE) @Casca
@OneToMany(cascade=CascadeType.REMOVE)
但这会给出“on delete restrict”/不会更改默认的“on delete restrict”?试试这个
@OneToMany(mappedBy = "parent", cascade = javax.persistence.CascadeType.REMOVE)
@Cascade(org.hibernate.annotations.CascadeType.DELETE_ORPHAN)
您需要在父类上使用注释,以便Hibernate在DDL中生成它(@OnDelete(action=OnDeleteAction.CASCADE)
)
例如:
@Entity
class Parent {
/* id and some attributes */
@OneToMany(mappedBy = "parent", cascade = {CascadeType.REMOVE})
@ForeignKey(name = "FK_CHILD_PARENT")
@OnDelete(action = OnDeleteAction.CASCADE)
List<Child> children;
}
@Entity
class Child {
/* id and some attributes */
Parent parent;
}
@实体
班级家长{
/*id和一些属性*/
@OneToMany(mappedBy=“parent”,cascade={CascadeType.REMOVE})
@ForeignKey(name=“FK\u CHILD\u PARENT”)
@OnDelete(action=OnDeleteAction.CASCADE)
列出儿童名单;
}
@实体
班童{
/*id和一些属性*/
父母;
}
尽管您要求将“on delete cascade”作为DDL,但我的回答涵盖了软件级别。EBean似乎不会产生DB级级联。相反,它在软件中处理级联操作。我认为这是一个很好的选择
参见(avaje-ebeanorm-4.6.2.jar:com/avaje/ebeaninternal/server/persist/DefaultPersister)
/**
*删除bean。
*
*请注意,preDelete在删除子项之前激发。
*
*/
私有void删除(PersistRequestBean请求){
DeleteUnloadedForeignKeys unloadedForeignKeys=null;
if(request.isPersistCascade()){
//首先删除子项…注册
//处理双向级联的bean
request.registerDeleteBean();
deleteAssocMany(请求);
request.unregisterDeleteBean();
...
您可以看到,如果请求是级联的,那么首先会删除它的子级(可能这是递归的)
在我的postgre DB中,自动生成的外键约束不包含任何级联,但删除操作仍然是级联的
/**
* Delete the bean.
* <p>
* Note that preDelete fires before the deletion of children.
* </p>
*/
private void delete(PersistRequestBean<?> request) {
DeleteUnloadedForeignKeys unloadedForeignKeys = null;
if (request.isPersistCascade()) {
// delete children first ... register the
// bean to handle bi-directional cascading
request.registerDeleteBean();
deleteAssocMany(request);
request.unregisterDeleteBean();
...