JPA + Hibernate：如何定义一个具有ON DELETE CASCADE的约束 [英] JPA + Hibernate: How to define a constraint having ON DELETE CASCADE

问题描述

我只是想知道是否有这样的方式可以将我的MySQL表构建为

  ALTER TABLE`USERINFO` 
 ADD CONSTRAINT`FK_USER_ID` FOREIGN KEY（`USERID`）REFERENCES`USERACCOUNT`（`USERID`）
 ON DELETE CASCADE 
 ON UPDATE CASCADE; 
  

然而，我只在DDL中得到这个，当hibernate ++ jpa开始构建我的表时， < property name =hibernate.hbm2ddl.autovalue =create/>

  ALTER TABLE'USERINFO'ADD CONSTRAINT'FK_USER_ID` FOREIGN KEY（`USERID`）REFERENCES`USERACCOUNT`（`USERID`）; 
  

在我的课程中，我有这些注释设置，

  // UserAcc.java 
 @Entity 
 @Table（name =USERACC）
 public class UserAcc实现Serializable {
 
 private static final long serialVersionUID = -5527566248002296042L; 
 
 @Id 
 @Column（name =USERID）
 @GeneratedValue（strategy = GenerationType.AUTO）
 private Integer userId; 
 
 
 @OneToOne（mappedBy =userAcc）
 private UserInfo userInfo; 
 .... 
 
 
 public UserInfo getUserInfo（）{
 return userInfo; 
} 
 public void setUserInfo（UserInfo userInfo）{
 this.userInfo = userInfo; 
} 
 ... 
  

和

// UserInfo.java
@Entity
@Table（name =USERINFO）
public class UserInfo实现Serializable {

private static final long serialVersionUID = 5924361831551833717L;

@Id
@Column（name =USERINFO_ID，nullable = false）
@GeneratedValue（strategy = GenerationType.AUTO）
private Integer userInfoId;

@OneToOne（cascade = {CascadeType.ALL}）
@JoinColumn（name =USERID，nullable = false）
@ForeignKey（name =FK_USER_ID）
private UserAcc userAcc;


public Integer getUserInfoId（）{
return userInfoId;
}

public void setUserInfoId（Integer userInfoId）{
this.userInfoId = userInfoId;




$ b注意，UserAccount表是父/主表，而UserInfo是一个扩展表，规范化为另一个实体。任何答案将不胜感激。我只是好奇它是如何完成的，因为我喜欢在MySQL中工作。我真的很习惯从父表（USERACOUNT）中删除一条记录，这将允许我通过父级/主表中的特定记录级联删除通过子记录。

谢谢！

解决方案

JPA提供了级联操作（合并，保留，刷新，删除）到关联的实体。逻辑在JPA中，不使用数据库级联。

  @OneToMany（cascade = CascadeType.REMOVE）
  code> 

没有符合JPA标准的方式来执行数据库级联级联。如果这样的级联是首选，我们必须回到Hibernate特定的结构： @OnDelete 。它至少与@OneToMany一起工作，但过去曾出现过一些与@OneToOne和@OnDelete有关的问题。

  @ OnDelete（action = OnDeleteAction.CASCADE）
  




I am just wondering if there's such a way that I can have build my MySQL table as

ALTER TABLE `USERINFO`
  ADD CONSTRAINT `FK_USER_ID` FOREIGN KEY (`USERID`) REFERENCES `USERACCOUNT` (`USERID`) 
    ON DELETE CASCADE 
    ON UPDATE CASCADE;

However, I only got this in my DDL when hibernate ++ jpa starts to build my table having "<property name="hibernate.hbm2ddl.auto" value="create" />"

ALTER TABLE `USERINFO` ADD CONSTRAINT `FK_USER_ID` FOREIGN KEY (`USERID`) REFERENCES `USERACCOUNT` (`USERID`);

In my classes, I have these annotation setup,

// UserAcc.java
@Entity
@Table(name = "USERACC")
public class UserAcc implements Serializable {

private static final long serialVersionUID = -5527566248002296042L;

@Id
@Column(name = "USERID")
@GeneratedValue(strategy=GenerationType.AUTO)
private Integer userId;


@OneToOne(mappedBy = "userAcc")
private UserInfo userInfo;
....


public UserInfo getUserInfo() {
    return userInfo;
}
public void setUserInfo(UserInfo userInfo) {
    this.userInfo = userInfo;
}
...

and,

// UserInfo.java
@Entity
@Table(name = "USERINFO")
public class UserInfo implements Serializable {

private static final long serialVersionUID = 5924361831551833717L;

@Id
@Column(name = "USERINFO_ID", nullable=false)
@GeneratedValue(strategy=GenerationType.AUTO)
private Integer userInfoId;

@OneToOne(cascade = {CascadeType.ALL})
@JoinColumn(name="USERID", nullable=false)
@ForeignKey(name = "FK_USER_ID")
private UserAcc userAcc;


public Integer getUserInfoId() {
    return userInfoId;
}

public void setUserInfoId(Integer userInfoId) {
    this.userInfoId = userInfoId;
}
...

Note that, UserAccount table is the parent/main table here while UserInfo is an extended table normalize to another entity. Any answers would be greatly appreciated. I'm just curious how it's done as I love to work also in MySQL. I am just really used to deleting a record from the parent table (USERACOUNT) which would would also allow me to cascade a delete thru child records dependent on the specific record from a parent/primary table.

Thanks!

解决方案

JPA do offer possibility to cascade operations (merge, persist, refresh, remove) to associated entities. Logic is in JPA and does not utilize database cascades.

@OneToMany(cascade=CascadeType.REMOVE)

There is no JPA standard compliant way to do cascades with database cascades. If such a cascades are preferred, we have to fall back to Hibernate specific construct: @OnDelete. It works with @OneToMany at least, but there used to be some problems in the past with @OneToOne and @OnDelete.

@OnDelete(action = OnDeleteAction.CASCADE)

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