有没有办法将分离的对象传递给JPA？ （传递给持久化的分离实体） [英] Is there a way to pass detached object to JPA persist? (detached entity passed to persist)

问题描述

我有两个实体：帐户和 AccountRole 。

  public class Account {
 private AccountRole accountRole; 
 
 @ManyToOne（cascade = CascadeType.PERSIST，fetch = FetchType.EAGER）
 public AccountRole getAccountRole（）{
 return accountRole; 
} 
  

。

  public class AccountRole {
 private Collection< Account> accounts = new ArrayList< Account>（）; 
 
 @OneToMany（mappedBy =accountRole，fetch = FetchType.EAGER）
 public Collection< Account> getAccounts（）{
返回帐户; 
 
 
 
 
 
 $ b 
问题出在我从数据库中取出accountRole并试图保存我的帐户。 此时，我刚刚创建了我的账户和角色，并已存在于db中。  
 
 
  AccountRole role = accountService .getRoleFromDatabase（AccountRoles.ROLE_USER）; 
 account.setAccountRole（role）; 
 
 //根据建议设置两种方式
 public void setAccountRole（AccountRole accountRole）{
 accountRole.addAccount（this）; 
 this.accountRole = accountRole; 
} 
 
 entityManager.persist（account）; //终于在我的DAO 
  
我读了这个： 我的理解是，我必须设置两个实体的值方向，这样我在我的setter中做的事。 
 
 
 
仍然出错。 
 
 
  org.hibernate.PersistentObjectException：传递给persist的分离实体：foo.bar.pojo.AccountRole 
  
 
只需将 
 
 
  entityManager.persist（account）替换为 ; 
  
附带： 
 
 
  entityManager.merge（帐户）; 
  
并允许合并级联： 
 
 <$ p $ 
 public AccountRole getAccountRole（）{
 return accountRole; $ {code> @ManyToOne（cascade = {CascadeType.PERSIST，CascadeType.MERGE}，fetch = FetchType.EAGER） 
 
 $ / code> 

因为合并是这样做的：



如果您的实体是新的，则它与persist（）相同。
但是如果您的实体已经存在，它会更新它。




I have 2 entities : Account and AccountRole.

public class Account {
   private AccountRole accountRole;

   @ManyToOne(cascade = CascadeType.PERSIST, fetch = FetchType.EAGER)
   public AccountRole getAccountRole() {
      return accountRole;
   }

.

public class AccountRole {
    private Collection<Account> accounts = new ArrayList<Account>();

    @OneToMany(mappedBy = "accountRole", fetch = FetchType.EAGER)
    public Collection<Account> getAccounts() {
         return accounts;
    }

Problem comes when I take the accountRole from database and try to persist my Account. At this point I just created my account and role already exists in db.

AccountRole role = accountService.getRoleFromDatabase(AccountRoles.ROLE_USER);
account.setAccountRole(role);

//setting both ways, as suggested
public void setAccountRole(AccountRole accountRole) {
    accountRole.addAccount(this);
    this.accountRole = accountRole;
}

entityManager.persist(account); // finally in my DAO

I read this : JPA/Hibernate: detached entity passed to persist And what I understood, I must set the entities values from both direction, so that what I am doing in my setter.

Still getting error.

 org.hibernate.PersistentObjectException: detached entity passed to persist: foo.bar.pojo.AccountRole

解决方案

Just replace the

entityManager.persist(account);

with:

entityManager.merge(account);

And allow merge cascading:

@ManyToOne(cascade = { CascadeType.PERSIST, CascadeType.MERGE }, fetch = FetchType.EAGER)
public AccountRole getAccountRole() {
    return accountRole;
}

Because merge does this:

If your entity is new, it's the same as a persist(). But if your entity already exists, it will update it.

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