Nhibernate多对多映射

时间：2011-03-11 来源：str.chan

一般来说多对多映射，映射表不需要设置为实体类，但如果特殊需求，如需要添加字段isActived等，这个时候就需要将映射表设置为实体，同时该实体需要针对两边的类做many-to-one映射，而两边的类需要做<bag><one-to-many>来实现双向关联，如下例：

需求：系统需要对私人(AccountInfo)发送短消息(Message)，同时要统计短消息阅读状态(IsReaded)，这时数据表设计如下：

首先是实体类的设计：
a.Message类

1     /// <summary>
2     /// 消息持久类
3     /// </summary>
4     [Serializable]
5     public class Message : MessageBase
6     {
7         /// <summary>
8         /// 该消息的帐户阅读状态
9         /// </summary>
10         public virtual IList<AccountMessage> Accounts{ get; set; }
11     }     Message映射文件
1 <?xml version="1.0" encoding="utf-8" ?>
2 <hibernate-mapping xmlns="urn:nhibernate-mapping-2.2"  assembly="YBValidator.Infrastructure.Core" namespace="YBValidator.Infrastructure.Core">
3   <class name="YBValidator.Infrastructure.Core.Message" table="Message">
4     <id name="ID" column="MsgID" type="int">
5       <generator class="native"></generator>
6     </id>
7
8     <property name="Title" column="Title" type="string" />
9     <property name="InputDate" column="InputDate" type="DateTime" />
10     <property name="Content" column="MsgContent" type="string" />
11
12     
13     <many-to-one name="User" column="UserName" not-null="true"
14                  foreign-key="FK_Message_UserInfo"
15                  ></many-to-one>
16
17     
18     <bag name="Accounts" cascade="all" inverse="true">
19       <key column="MsgID"></key>
20       <one-to-many class="AccountMessage"/>
21     </bag>
22   </class>
23 </hibernate-mapping>     b.AccountMessage类 1     [Serializable]
2     public class AccountMessage : Entity
3     {
4         public virtual int ID { get; set; }
5
6         public virtual bool IsReaded { get; set; }
7
8         public virtual Message Message { get; set; }
9
10         public virtual AccountInfo Account { get; set; }
11     }     AccountMessage映射文件 1 <?xml version="1.0" encoding="utf-8" ?>
2 <hibernate-mapping xmlns="urn:nhibernate-mapping-2.2"  assembly="YBValidator.Infrastructure.Core" namespace="YBValidator.Infrastructure.Core">
3   <class name="YBValidator.Infrastructure.Core.AccountMessage" table="AccountMessage" dynamic-insert="true" dynamic-update="true">
4     <id name="ID" column="ID" type="int">
5       <generator class="native"></generator>
6     </id>
7     <property name="IsReaded" column="IsReaded"></property>
8
9     
10
11     <many-to-one class="Message" name="Message" foreign-key="FK_AccountMessage_Message" column="MsgID"></many-to-one>
12
13     <many-to-one class="AccountInfo" name="Account" foreign-key="FK_AccountMessage_AccountInfo" column="AccName"></many-to-one>
14   </class>
15 </hibernate-mapping> 如上所示，在映射类(AccountMessage)中对两边的类(Message、AccountInfo)做两个many-to-one映射，而在两边的类（以Message为例），需要做一个one-to-many的映射来实现双相关联

    使用的时候就有点麻烦： 1                 IList<AccountMessage> accountMessages = new List<AccountMessage>();
2                 // 获取type相同的所有帐户
3                 var accountInfos = accountInfoFacade.GetAccountListByShopType(type);
4                 // 遍历帐户设置设置AccountMessage
5                 foreach (var accountInfo in accountInfos)
6                 {
7                     accountMessages.Add(new AccountMessage
8                                             {
9                                                 Account = accountInfo,
10                                                 Message = message
11                                             });
12                 }
13
14
15                 message.Accounts = accountMessages;