@OneToMany JPA注释导致不必要的sql更新，不会级联 [英] @OneToMany JPA annotation causes unnecessary sql update and doesn't cascade

问题描述

我正在将我的应用程序从基于xml的映射迁移到基于JPA注解的映射。但是这只会在一个简单的情况下失败。例如，我有以下3个实体：

  @Entitiy 
 public class UserAccount {
 
 @OneToMany（cascade = CascadeType.ALL，orphanRemoval = true）
 @JoinColumn（name =user_account_id，nullable = false，
 insertable = true，updatable = false）
 @ NotNull 
私人设置< Authority>当局; 
 
 @OneToOne（cascade = CascadeType.ALL）
 @JoinColumn（name =USER_ID，nullable = false）
 
 ... get和setter 
 
 
 @Entity 
公共类授权{
 
 @Column 
私有字符串权限; 
 
 ... get和setter 
} 
 
 @实体
公共类用户{
 ...一些属性
 } 
  

如果我创建一个新的UserAccount实例并尝试保存它，我得到一个异常，因为权限实例没有保存，这意味着它不像它应该做的那样级联。

  org.springframework.dao .InvalidDataAccessApiUsageException：
 org.hibernate.TransientObjectException：对象引用一个未保存的瞬态
实例 - 在冲洗前保存瞬态实例：Authority ... 
   
 
发生这种情况是因为hibernate尝试更新权限行（以前没有插入）： 
 
 <$ p $ h 
 
 
 
 
 Hibernate：
插入user_accounts ... 
 
 Hibernate： 
更新权限设置user_account_id =？其中id =？ 
  

我使用以下服务保存UserAccount实例。

  @Service 
 public class UserAccountService {
 
 @Resource 
 private UserAccountRepository userAccountRepository; 
 
 @Transactional（propagation = Propagation.REQUIRED，readOnly = false）
 public void save（UserAccount userAccount）{
 
 userAccountRepository.save（userAccount）; 
 
 
 
 
 
 
奇怪的是，用户实例将被保存，所以OneToOne映射级联（如果我删除了UserAccount.authorities属性）。但是，这与基于xml的映射（并且没有JPA）一起工作。我最终调用了一个单独的方法来存储Authoriy实例。 
 
 
  @Service 
 public class UserAccountService {
 
 @Resource 
 private UserAccountRepository userAccountRepository; 
 @Resource 
 private AuthorityRepository authorityRepository; 
 
 @Transactional（propagation = Propagation.REQUIRED，readOnly = false）
 public void save（UserAccount userAccount）{
 
 userAccountRepository.save（userAccount）; 
 authorityRepository.save（userAccount.getAuthoritiesSet（））; 
} 
 
} 
  
这意味着，我手动级联。但是，查看执行的SQL语句，我可以看到，hibernate插入了权限实例，之后，它更新此行以设置UserAccount引用：
 
 
 <$ p $ b $  Hibernate：
插入用户... 
 
 Hibernate：
插入user_accounts ... 
 
 Hibernate ：
插入权限（权限）值（？）
 
 Hibernate：
更新权限集user_account_id =？其中id =？ 
  

对于我来说这是一个性能问题，因为有很多权限，我不想拥有20次插入，之后20次更新。但我无法删除更新，并告诉hibernate将user_account_id与权限一起设置。

因为我还有许多其他有OneToMany关系的对象，所以我我对解决这个问题非常感兴趣，并感谢您的帮助和想法。

Hibernate：4.3.4.Final，
spring data jpa：1.5.1.RELEASE

祝好，
Daniel

解决方案

我与ManyToOne映射有类似的问题。
通过向版本字段添加默认值解决了问题。

  @Version 
 @Column（name = VERSION）
 private Integer version = 1; 
  

I am migrating my app from xml based mapping to JPA annotation based mapping. But this fails only in a simple case. For example, I've the following 3 entities:

@Entitiy
public class UserAccount {

     @OneToMany(cascade = CascadeType.ALL, orphanRemoval = true)
     @JoinColumn(name = "user_account_id", nullable = false, 
                 insertable = true, updatable = false)
     @NotNull
     private Set<Authority> authorities;

     @OneToOne(cascade = CascadeType.ALL)
     @JoinColumn(name="USER_ID", nullable = false)

     ... get and setter
}

@Entity
public class Authority {

    @Column
    private String authority;

    ... get and setter
}

@Entity
public class User {
    ... some properties
}

If I create a new UserAccount instance and try to save it, I got an exception, because the Authority instance wasn't saved, which means, it doesn't cascade as it supposed to do.

org.springframework.dao.InvalidDataAccessApiUsageException: 
org.hibernate.TransientObjectException: object references an unsaved transient 
instance - save the transient instance before flushing: Authority ...

This happens, because hibernate tries to update the authority row (which wasn't inserted before):

Hibernate: 
    insert into users ...

Hibernate: 
    insert into user_accounts ...

Hibernate: 
    update authorities set user_account_id=? where id=?

I used the following service to save the UserAccount instance.

@Service
public class UserAccountService {

    @Resource
    private UserAccountRepository userAccountRepository;

    @Transactional(propagation = Propagation.REQUIRED, readOnly = false)
    public void save(UserAccount userAccount) {

       userAccountRepository.save(userAccount);
    }

}

The strange thing is, that the User instance will be saved, so the OneToOne mapping cascades (if I remove the UserAccount.authorities property). But this worked with the xml based mapping (and without JPA). I ended up in calling a separate method to store the Authoriy instances.

@Service
public class UserAccountService {

    @Resource
    private UserAccountRepository userAccountRepository;
    @Resource
    private AuthorityRepository authorityRepository;

    @Transactional(propagation = Propagation.REQUIRED, readOnly = false)
    public void save(UserAccount userAccount) {

        userAccountRepository.save(userAccount);
        authorityRepository.save(userAccount.getAuthoritiesSet());
    }

} 

Which means, I cascade manually... However, looking into the executed SQL statements, I can see, that hibernate inserts the authority instance and after that, it updates this row to set the UserAccount reference:

Hibernate: 
    insert into users ...

Hibernate: 
    insert into user_accounts ...

Hibernate: 
    insert into authorities (authority) values (?)

Hibernate: 
    update authorities set user_account_id=? where id=?

And for me this is a performance issue, because there are many authorities and I do not want to have 20 inserts and after that 20 updates. But I was not able to "remove" the updates and tell hibernate to set the user_account_id together with the authority.

Because I've many other objects having OneToMany relations, I am very interested in resolving this problem and appreciate your help and thoughts.

Hibernate: 4.3.4.Final, spring data jpa: 1.5.1.RELEASE

Best regards, Daniel

解决方案

I had very similar issue with ManyToOne mapping. Solved problem by adding default value to version field.

@Version
@Column(name = "VERSION")
private Integer version = 1;

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