Nhibernate:映射一对多关系时出现问题
本文关键字:问题 关系 映射 一对多 Nhibernate | 更新日期: 2023-09-27 18:21:24
我对nhibernate非常非常陌生,我确信这里有很多明显的事情我忽略了,但我已经寻找答案几天了,根本找不到适合我特定问题的解决方案。我真的非常感谢你的帮助。
我将首先描述我的问题,然后发布代码:
在我的对象模型中,我有一个IList为"Organizer"的"Event"。我想使用nhibernate,这样当我执行"session.Save(anEvent)"时,数据会写入数据库中的三个表:Events、Organizers和Organizers_Events(联接表)。当我使用以下代码时,我会得到以下错误:
Invalid column name 'EventID'
我的代码:首先,.hbm文件:
<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2"
assembly="BLL"
namespace="BusinessLogic">
<class name="Event" table="Events">
<id name="EventID">
<column name="ID"/>
<generator class="native" />
</id>
<property name="Name">
<column name="Name"/>
</property>
<bag name="Organizers" table="Organizers_Events" inverse="false" cascade="all-delete-orphan" lazy="true" access="nosetter.camelcase-underscore" >
<key column="EventID"/>
<one-to-many class="Organizer" />
</bag>
</class>
</hibernate-mapping>
<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2"
assembly="BLL"
namespace="BusinessLogic">
<class name="Organizer" table="Organizers">
<id name="Id">
<column name="ID"/>
<generator class="native" />
</id>
<property name="FullName">
<column name="FullName"/>
</property>
<many-to-one name="TheEvent" column="EventID" />
</class>
</hibernate-mapping>
接下来,对象:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
/// <summary>
/// Summary description for Event
/// </summary>
///
namespace BusinessLogic
{
public class Event
{
private int eventID;
public virtual int EventID
{
get { return eventID; }
set { eventID = value; }
}
private IList<Organizer> _organizers = null;
public virtual IList<Organizer> Organizers
{
get { return _organizers; }
set { _organizers = value; }
}
public Event()
{
//
// TODO: Add constructor logic here
//
}
}
}
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
namespace BusinessLogic
{
public class Organizer:Invitee
{
private Event theEvent = new Event();
public virtual Event TheEvent
{
get { return theEvent; }
set { theEvent = value; }
}
}
}
最后,数据库模式:
CREATE TABLE [dbo].[Events](
[ID] [int] IDENTITY(1,1) NOT NULL,
[Name] [nvarchar](max) NOT NULL
) ON [PRIMARY]
CREATE TABLE [dbo].[Organizers](
[ID] [int] IDENTITY(1,1) NOT NULL,
[FullName] [nvarchar](550) NULL
) ON [PRIMARY]
CREATE TABLE [dbo].[Organizers_Events](
[OrganizerID] [int] NOT NULL,
[EventID] [int] NOT NULL
) ON [PRIMARY]
为了简化问题,我删掉了不相关的数据。我不认为其他任何事情对我的问题有任何影响。出于我们的目的,我只希望Event对象将其EventID和Name写入Events表,IList中的每个组织者对象将其ID和FullName写入Organizers表,EventID和organizer的ID写入Organizers_Events表。
我做错了什么?如果有很多,请告诉我。或者,如果网上已经有我错过的答案,请直接告诉我。
在一对多关联中,不需要联接表。只有在多对多关联中才需要联接表。正确映射
<bag name="Organizers" inverse="false" cascade="all-delete-orphan" lazy="true" access="nosetter.camelcase-underscore" >
<key column="EventID"/>
<one-to-many class="Organizer" />
</bag>
一对多关联的正确数据库模式
CREATE TABLE [dbo].[Events]
(
[ID] [int] IDENTITY(1,1) NOT NULL,
[Name] [nvarchar](max) NOT NULL
)
ON [PRIMARY]
CREATE TABLE [dbo].[Organizers]
(
[ID] [int] IDENTITY(1,1) NOT NULL,
[FullName] [nvarchar](550) NULL,
[EventID] [int] NOT NULL // add FK constraint here
)
ON [PRIMARY]
我想你忘了在包声明中放inverse="false":
<bag name="Organizers" inverse="false" table="Organizers_Events" cascade="all-delete-orphan" lazy="true" access="nosetter.camelcase-underscore" >