java - 无法持久保存附加现有对象的新对象

Question

我是一个新的 Hibernate 用户，我认为应该是一个非常简单的操作，这让我感到困惑。我正在尝试从数据库加载用户，将其附加到新对象，然后保留该新对象。我发现违反了空约束。

我的理解是，如果在数据库中找不到 AdmUser 对象，load() 方法会引发异常。为了确定，我查了一下，它绝对不为空。我知道它可能是代理，但我在同一个 session 中，所以这不应该是问题，对吧？我在这里做错了什么？

审核日志 POJO:

public class AdmAuditLog implements java.io.Serializable {

    private AdmUser actionBy;
    // ...

    public AdmAuditLog() {
    }

    public AdmUser getActionBy() {
        return this.actionBy;
    }

    public void setActionBy(final AdmUser actionBy) {
        this.actionBy = actionBy;
    }

    // ...
}

AdmAuditLog.hbm.xml:

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
<hibernate-mapping>
    <class name="com.locustec.lotus.db.admin.AdmAuditLog" table="ADM_AUDIT_LOG">
        <id ... />
        <property ... />
        <one-to-one name="actionBy" class="com.locustec.lotus.db.admin.AdmUser" fetch="join" lazy="false" />
    </class>
</hibernate-mapping>

源代码:

final Session session = ...;
final Transaction transaction = session.beginTransaction();

final AdmUser user =
        (AdmUser) asess.load(AdmUser.class, userId);
LOGGER.error("User {} = {}", user.getFullName(), user);

final AdmAuditLog adm = new AdmAuditLog();
adm.setXXX(xxx);
// more setters
adm.setActionBy(user);

session.save(adm);
transaction.commit();

日志文件:

20:04:47,900 ERROR User Eric Stein = com.mycompany.myproduct.db.admin.AdmUser@7b2792a0
20:04:49,578 WARN  SQL Error: 515, SQLState: 23000
20:04:49,579 ERROR Cannot insert the value NULL into column 'ACTION_BY', table 'MyDatabase.dbo.ADM_AUDIT_LOG'; column does not allow nulls. INSERT fails.

审核日志 DDL:

USE [MyDatabase]
GO

/****** Object:  Table [dbo].[ADM_AUDIT_LOG]    Script Date: 09/12/2014 20:09:55 ******/
SET ANSI_NULLS ON
GO

SET QUOTED_IDENTIFIER ON
GO

CREATE TABLE [dbo].[ADM_AUDIT_LOG](
    [ALID] [int] NOT NULL,
    [SCOPE_ID] [bigint] NOT NULL,
    [SCOPE] [nvarchar](100) NOT NULL,
    [ACTIVITY_ID] [bigint] NOT NULL,
    [ACTIVITY] [nvarchar](100) NOT NULL,
    [ELEMENT_ID] [bigint] NULL,
    [ELEMENT] [nvarchar](200) NULL,
    [DETAIL] [nvarchar](2000) NULL,
    [ACTION_BY] [bigint] NOT NULL,
    [ACTION_DATE] [datetime] NOT NULL,
    [ACTION_FROM] [nvarchar](50) NULL,
 CONSTRAINT [PK_ADM_AUDIT_LOG] PRIMARY KEY CLUSTERED 
(
    [ALID] ASC
)WITH (PAD_INDEX  = OFF, STATISTICS_NORECOMPUTE  = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS  = ON, ALLOW_PAGE_LOCKS  = ON) ON [PRIMARY]
) ON [PRIMARY]

GO

我想这就是全部了。如果还有其他有帮助的事情，请不要羞于询问。

Answer 1

一对一元素用于双向一对一关联的“反向”端。

一对一元素不映射到数据库外键。您需要使用独特的多对一来代替:

<many-to-one 
    name="actionBy" 
    class="com.locustec.lotus.db.admin.AdmUser" 
    fetch="join" 
    lazy="false" 
    unique="true"
    not-null="true"/>

多对一元素能够控制 FK，因此它将保留映射。