IBaitsNet的对象关系一对多实现
看了园子里很多IBatisNet的文章，感觉对实体一对多关系的配置都没有详细的解释，
这段时间空闲时间比较多一点，对使用IBatisNet的一些体会进行整理，在这里感觉善友大哥，
我IBatis的入门就是看的他的文章，这个demo也是改的他的代码。
hibernate 的强大在于完全的对象化，对于对象之间的关系解决的比较好，
如1对1，1对多，多对1，以及多对多。当然也包括继承关系。而ibatis这方面就比较逊色了，
不过对于也支持简单的关连查询，如1对1，和1对多。对于一般的情况来说，这两种已经足够了。
下面进入正文讲一下IBatisNet的一对多配置。
开发环境：VS2005 SqlServer2000 IBatisNet框架（IBatisNet.DataMapper1.6.1）
主要内容：1．准备数据表结构 2．编写实体类 3．构建配置信息
1.准备数据表结构
在这个例子中，我们引入了两个对象User、Post，它们之间的关系是一对多，即一个User有多篇Post。需要用到的数据表结构如下
User类的配置文件
需要注意的是，这里有一个潜在的性能问题，也就是所谓“n+1”Select问题，但IBatisNet支持懒加载lazyLoad="true"，来解决这个性能问题。
这段时间空闲时间比较多一点，对使用IBatisNet的一些体会进行整理，在这里感觉善友大哥，
我IBatis的入门就是看的他的文章，这个demo也是改的他的代码。
hibernate 的强大在于完全的对象化，对于对象之间的关系解决的比较好，
如1对1，1对多，多对1，以及多对多。当然也包括继承关系。而ibatis这方面就比较逊色了，
不过对于也支持简单的关连查询，如1对1，和1对多。对于一般的情况来说，这两种已经足够了。
下面进入正文讲一下IBatisNet的一对多配置。
开发环境：VS2005 SqlServer2000 IBatisNet框架（IBatisNet.DataMapper1.6.1）
主要内容：1．准备数据表结构 2．编写实体类 3．构建配置信息
1.准备数据表结构
在这个例子中，我们引入了两个对象User、Post，它们之间的关系是一对多，即一个User有多篇Post。需要用到的数据表结构如下
CREATE TABLE Users (
UserID int identity NOT NULL,
UserName nvarchar(40) NOT NULL,
Password nvarchar(20) NOT NULL,
EmailAddress nvarchar(40) NOT NULL,
LastLogon datetime,
PRIMARY KEY (UserID)
)
CREATE TABLE Posts (
PostID int identity NOT NULL,
Title nvarchar(100) NOT NULL,
Message ntext,
CreatedDate datetime,
ModifiedDate datetime,
UserID int NOT NULL,
PRIMARY KEY (PostID),
FOREIGN KEY (UserID) References Users(UserID)
)
2.编写实体类UserID int identity NOT NULL,
UserName nvarchar(40) NOT NULL,
Password nvarchar(20) NOT NULL,
EmailAddress nvarchar(40) NOT NULL,
LastLogon datetime,
PRIMARY KEY (UserID)
)
CREATE TABLE Posts (
PostID int identity NOT NULL,
Title nvarchar(100) NOT NULL,
Message ntext,
CreatedDate datetime,
ModifiedDate datetime,
UserID int NOT NULL,
PRIMARY KEY (PostID),
FOREIGN KEY (UserID) References Users(UserID)
)
public class User
{
#region UserID
private Int32 m_userID;
/// <summary>Gets or sets UserID</summary>
public Int32 UserID
{
get { return m_userID; }
set { m_userID = value; }
}
#endregion
#region UserName
private String m_userName;
/// <summary>Gets or sets UserName</summary>
public String UserName
{
get { return m_userName; }
set { m_userName = value; }
}
#endregion
#region Password
private String m_password;
/// <summary>Gets or sets Password</summary>
public String Password
{
get { return m_password; }
set { m_password = value; }
}
#endregion
#region EmailAddress
private String m_emailAddress;
/// <summary>Gets or sets EmailAddress</summary>
public String EmailAddress
{
get { return m_emailAddress; }
set { m_emailAddress = value; }
}
#endregion
#region LastLogon
private DateTime? m_lastLogon;
/// <summary>Gets or sets LastLogon</summary>
public DateTime? LastLogon
{
get { return m_lastLogon; }
set { m_lastLogon = value; }
}
#endregion
private IList<Post> m_postList;
public IList<Post> Posts
{
get { return m_postList; }
set { m_postList = value; }
}
}
public class Post
{
#region PostID
private Int32 m_postID;
/// <summary>Gets or sets PostID</summary>
public Int32 PostID
{
get { return m_postID; }
set { m_postID = value; }
}
#endregion
#region Title
private String m_title;
/// <summary>Gets or sets Title</summary>
public String Title
{
get { return m_title; }
set { m_title = value; }
}
#endregion
#region Message
private String m_message;
/// <summary>Gets or sets Message</summary>
public String Message
{
get { return m_message; }
set { m_message = value; }
}
#endregion
#region CreatedDate
private DateTime? m_createdDate;
/// <summary>Gets or sets CreatedDate</summary>
public DateTime? CreatedDate
{
get { return m_createdDate; }
set { m_createdDate = value; }
}
#endregion
#region ModifiedDate
private DateTime? m_modifiedDate;
/// <summary>Gets or sets ModifiedDate</summary>
public DateTime? ModifiedDate
{
get { return m_modifiedDate; }
set { m_modifiedDate = value; }
}
#endregion
#region UserID
private User m_user;
/// <summary>Gets or sets UserID</summary>
public User User
{
get { return m_user; }
set { m_user = value; }
}
#endregion
}
3.编写配置文件{
#region UserID
private Int32 m_userID;
/// <summary>Gets or sets UserID</summary>
public Int32 UserID
{
get { return m_userID; }
set { m_userID = value; }
}
#endregion
#region UserName
private String m_userName;
/// <summary>Gets or sets UserName</summary>
public String UserName
{
get { return m_userName; }
set { m_userName = value; }
}
#endregion
#region Password
private String m_password;
/// <summary>Gets or sets Password</summary>
public String Password
{
get { return m_password; }
set { m_password = value; }
}
#endregion
#region EmailAddress
private String m_emailAddress;
/// <summary>Gets or sets EmailAddress</summary>
public String EmailAddress
{
get { return m_emailAddress; }
set { m_emailAddress = value; }
}
#endregion
#region LastLogon
private DateTime? m_lastLogon;
/// <summary>Gets or sets LastLogon</summary>
public DateTime? LastLogon
{
get { return m_lastLogon; }
set { m_lastLogon = value; }
}
#endregion
private IList<Post> m_postList;
public IList<Post> Posts
{
get { return m_postList; }
set { m_postList = value; }
}
}
public class Post
{
#region PostID
private Int32 m_postID;
/// <summary>Gets or sets PostID</summary>
public Int32 PostID
{
get { return m_postID; }
set { m_postID = value; }
}
#endregion
#region Title
private String m_title;
/// <summary>Gets or sets Title</summary>
public String Title
{
get { return m_title; }
set { m_title = value; }
}
#endregion
#region Message
private String m_message;
/// <summary>Gets or sets Message</summary>
public String Message
{
get { return m_message; }
set { m_message = value; }
}
#endregion
#region CreatedDate
private DateTime? m_createdDate;
/// <summary>Gets or sets CreatedDate</summary>
public DateTime? CreatedDate
{
get { return m_createdDate; }
set { m_createdDate = value; }
}
#endregion
#region ModifiedDate
private DateTime? m_modifiedDate;
/// <summary>Gets or sets ModifiedDate</summary>
public DateTime? ModifiedDate
{
get { return m_modifiedDate; }
set { m_modifiedDate = value; }
}
#endregion
#region UserID
private User m_user;
/// <summary>Gets or sets UserID</summary>
public User User
{
get { return m_user; }
set { m_user = value; }
}
#endregion
}
User类的配置文件
<?xml version="1.0" encoding="utf-8" ?>
<sqlMap namespace="User"
xmlns="http://ibatis.apache.org/mapping"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<alias>
<typeAlias alias="User" type="IBatisNetDemo.Domain.User,IBatisNetDemo" />
</alias>
<resultMaps>
<resultMap id="UserResult" class="User">
<result property="UserID" column="UserID" dbType="Int"/>
<result property="UserName" column="UserName" dbType="NVarChar"/>
<result property="Password" column="Password" dbType="NVarChar"/>
<result property="EmailAddress" column="EmailAddress" dbType="NVarChar"/>
<result property="LastLogon" column="LastLogon" dbType="DateTime"/>
</resultMap>
<resultMap id="User-Result" class="User" extends="UserResult">
<result property="Posts" resultMapping="Post.PostResult" />
</resultMap>
<resultMap id="User_Result" class="User" extends="UserResult">
<result property="Posts" column="UserID" lazyLoad="true" select="GetPostsForUser" />
</resultMap>
</resultMaps>
<statements>
<select id="FindAllUser" resultMap="User_Result">
SELECT *
FROM [dbo].[Users]
</select>
<select id="GetAllUser" resultMap="User-Result">
select u.UserID,u.UserName,u.Password,u.EmailAddress,u.LastLogon
,p.PostID,p.Title,p.Message,p.CreatedDate,p.ModifiedDate
from Users u
left outer join Posts p
on u.UserID=p.UserID
</select>
<select id="FindByUserId" parameterClass="int" resultMap="User_Result">
SELECT *
FROM [dbo].[Users]
WHERE
([Users].[UserID] = #UserID,dbType=Int#)
</select>
<insert id="InsertUser" parameterClass="User">
<selectKey property="UserID" type="post" resultClass="int">
${selectKey}
</selectKey>
INSERT INTO [dbo].[Users] (
[UserName]
, [Password]
, [EmailAddress]
, [LastLogon]
) VALUES (
#UserName,dbType=NVarChar#
, #Password,dbType=NVarChar#
, #EmailAddress,dbType=NVarChar#
, #LastLogon,dbType=DateTime#
)
</insert>
<update id="UpdateUser" parameterClass="User">
UPDATE [dbo].[Users] SET
[UserName] = #UserName,dbType=NVarChar#
, [Password] = #Password,dbType=NVarChar#
, [EmailAddress] = #EmailAddress,dbType=NVarChar#
, [LastLogon] = #LastLogon,dbType=DateTime#
WHERE
([UserID] = #UserID,dbType=Int#)
</update>
<delete id="DeleteUser" parameterClass="int">
DELETE FROM [dbo].[Users]
WHERE
([UserID] = #UserID,dbType=Int#)
</delete>
</statements>
</sqlMap>
这里用两种方法实现了一对多关系，使用内在的resultMap解决问题完成一对多的映射<sqlMap namespace="User"
xmlns="http://ibatis.apache.org/mapping"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<alias>
<typeAlias alias="User" type="IBatisNetDemo.Domain.User,IBatisNetDemo" />
</alias>
<resultMaps>
<resultMap id="UserResult" class="User">
<result property="UserID" column="UserID" dbType="Int"/>
<result property="UserName" column="UserName" dbType="NVarChar"/>
<result property="Password" column="Password" dbType="NVarChar"/>
<result property="EmailAddress" column="EmailAddress" dbType="NVarChar"/>
<result property="LastLogon" column="LastLogon" dbType="DateTime"/>
</resultMap>
<resultMap id="User-Result" class="User" extends="UserResult">
<result property="Posts" resultMapping="Post.PostResult" />
</resultMap>
<resultMap id="User_Result" class="User" extends="UserResult">
<result property="Posts" column="UserID" lazyLoad="true" select="GetPostsForUser" />
</resultMap>
</resultMaps>
<statements>
<select id="FindAllUser" resultMap="User_Result">
SELECT *
FROM [dbo].[Users]
</select>
<select id="GetAllUser" resultMap="User-Result">
select u.UserID,u.UserName,u.Password,u.EmailAddress,u.LastLogon
,p.PostID,p.Title,p.Message,p.CreatedDate,p.ModifiedDate
from Users u
left outer join Posts p
on u.UserID=p.UserID
</select>
<select id="FindByUserId" parameterClass="int" resultMap="User_Result">
SELECT *
FROM [dbo].[Users]
WHERE
([Users].[UserID] = #UserID,dbType=Int#)
</select>
<insert id="InsertUser" parameterClass="User">
<selectKey property="UserID" type="post" resultClass="int">
${selectKey}
</selectKey>
INSERT INTO [dbo].[Users] (
[UserName]
, [Password]
, [EmailAddress]
, [LastLogon]
) VALUES (
#UserName,dbType=NVarChar#
, #Password,dbType=NVarChar#
, #EmailAddress,dbType=NVarChar#
, #LastLogon,dbType=DateTime#
)
</insert>
<update id="UpdateUser" parameterClass="User">
UPDATE [dbo].[Users] SET
[UserName] = #UserName,dbType=NVarChar#
, [Password] = #Password,dbType=NVarChar#
, [EmailAddress] = #EmailAddress,dbType=NVarChar#
, [LastLogon] = #LastLogon,dbType=DateTime#
WHERE
([UserID] = #UserID,dbType=Int#)
</update>
<delete id="DeleteUser" parameterClass="int">
DELETE FROM [dbo].[Users]
WHERE
([UserID] = #UserID,dbType=Int#)
</delete>
</statements>
</sqlMap>
<resultMap id="User-Result" class="User" extends="UserResult">
<result property="Posts" resultMapping="Post.PostResult" />
</resultMap>
<select id="GetAllUser" resultMap="User-Result">
select u.UserID,u.UserName,u.Password,u.EmailAddress,u.LastLogon
,p.PostID,p.Title,p.Message,p.CreatedDate,p.ModifiedDate
from Users u
left outer join Posts p
on u.UserID=p.UserID
</select>
还有就是在resultMap 中定义嵌套查询GetPostsForUser，实现了关联数据的读取。<result property="Posts" resultMapping="Post.PostResult" />
</resultMap>
<select id="GetAllUser" resultMap="User-Result">
select u.UserID,u.UserName,u.Password,u.EmailAddress,u.LastLogon
,p.PostID,p.Title,p.Message,p.CreatedDate,p.ModifiedDate
from Users u
left outer join Posts p
on u.UserID=p.UserID
</select>
需要注意的是，这里有一个潜在的性能问题，也就是所谓“n+1”Select问题，但IBatisNet支持懒加载lazyLoad="true"，来解决这个性能问题。
<resultMap id="User_Result" class="User" extends="UserResult">
<result property="Posts" column="UserID" lazyLoad="true" select="GetPostsForUser" />
</resultMap>
Post类的配置文件<result property="Posts" column="UserID" lazyLoad="true" select="GetPostsForUser" />
</resultMap>
<?xml version="1.0" encoding="utf-8" ?>
<sqlMap namespace="Post"
xmlns="http://ibatis.apache.org/mapping"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<alias>
<typeAlias alias="Post" type="IBatisNetDemo.Domain.Post,IBatisNetDemo" />
</alias>
<resultMaps>
<resultMap id="PostResult" class="Post">
<result property="PostID" column="PostID" dbType="Int"/>
<result property="Title" column="Title" dbType="NVarChar"/>
<result property="Message" column="Message" dbType="NText"/>
<result property="CreatedDate" column="CreatedDate" dbType="DateTime"/>
<result property="ModifiedDate" column="ModifiedDate" dbType="DateTime"/>
</resultMap>
<resultMap id="Post-Result" class="Post" extends="PostResult">
<result property="User" resultMapping="User.UserResult"/>
</resultMap>
</resultMaps>
<statements>
<select id="FindAllPost" resultMap="Post-Result">
select p.PostID,p.Title,p.Message,p.CreatedDate,p.ModifiedDate,
u.UserID,u.UserName,u.Password,u.EmailAddress,u.LastLogon
from Posts p,Users u
where p.UserID=u.UserID
</select>
<select id="GetAllPost" resultMap="PostResult">
select p.PostID,p.Title,p.Message,p.CreatedDate,p.ModifiedDate
from Posts p
</select>
<select id="FindByPostId" parameterClass="Post" resultMap="PostResult" extends="FindAllPost">
WHERE
([Posts].[PostID] = #PostID,dbType=Int#)
</select>
<select id="GetPostsForUser" parameterClass="int" resultMap="PostResult" extends="FindAllPost">
WHERE
([Posts].[UserID] = #User.UserID,dbType=Int#)
</select>
<insert id="InsertPost" parameterClass="Post">
<selectKey property="PostID" type="post" resultClass="int">
${selectKey}
</selectKey>
INSERT INTO [dbo].[Posts] (
[Title]
, [Message]
, [CreatedDate]
, [ModifiedDate]
, [UserID]
) VALUES (
#Title,dbType=NVarChar#
, #Message,dbType=NText#
, #CreatedDate,dbType=DateTime#
, #ModifiedDate,dbType=DateTime#
, #User.UserID,dbType=Int#
)
</insert>
<update id="UpdatePost" parameterClass="Post">
UPDATE [dbo].[Posts] SET
[Title] = #Title,dbType=NVarChar#
, [Message] = #Message,dbType=NText#
, [CreatedDate] = #CreatedDate,dbType=DateTime#
, [ModifiedDate] = #ModifiedDate,dbType=DateTime#
, [UserID] = #User.UserID,dbType=Int#
WHERE
([PostID] = #PostID,dbType=Int#)
</update>
<delete id="DeletePost" parameterClass="Post">
DELETE FROM [dbo].[Posts]
WHERE
([PostID] = #PostID,dbType=Int#)
</delete>
</statements>
</sqlMap>
小弟第一次把文章发在首页，诚惶诚恐，欢迎大家拍砖<sqlMap namespace="Post"
xmlns="http://ibatis.apache.org/mapping"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<alias>
<typeAlias alias="Post" type="IBatisNetDemo.Domain.Post,IBatisNetDemo" />
</alias>
<resultMaps>
<resultMap id="PostResult" class="Post">
<result property="PostID" column="PostID" dbType="Int"/>
<result property="Title" column="Title" dbType="NVarChar"/>
<result property="Message" column="Message" dbType="NText"/>
<result property="CreatedDate" column="CreatedDate" dbType="DateTime"/>
<result property="ModifiedDate" column="ModifiedDate" dbType="DateTime"/>
</resultMap>
<resultMap id="Post-Result" class="Post" extends="PostResult">
<result property="User" resultMapping="User.UserResult"/>
</resultMap>
</resultMaps>
<statements>
<select id="FindAllPost" resultMap="Post-Result">
select p.PostID,p.Title,p.Message,p.CreatedDate,p.ModifiedDate,
u.UserID,u.UserName,u.Password,u.EmailAddress,u.LastLogon
from Posts p,Users u
where p.UserID=u.UserID
</select>
<select id="GetAllPost" resultMap="PostResult">
select p.PostID,p.Title,p.Message,p.CreatedDate,p.ModifiedDate
from Posts p
</select>
<select id="FindByPostId" parameterClass="Post" resultMap="PostResult" extends="FindAllPost">
WHERE
([Posts].[PostID] = #PostID,dbType=Int#)
</select>
<select id="GetPostsForUser" parameterClass="int" resultMap="PostResult" extends="FindAllPost">
WHERE
([Posts].[UserID] = #User.UserID,dbType=Int#)
</select>
<insert id="InsertPost" parameterClass="Post">
<selectKey property="PostID" type="post" resultClass="int">
${selectKey}
</selectKey>
INSERT INTO [dbo].[Posts] (
[Title]
, [Message]
, [CreatedDate]
, [ModifiedDate]
, [UserID]
) VALUES (
#Title,dbType=NVarChar#
, #Message,dbType=NText#
, #CreatedDate,dbType=DateTime#
, #ModifiedDate,dbType=DateTime#
, #User.UserID,dbType=Int#
)
</insert>
<update id="UpdatePost" parameterClass="Post">
UPDATE [dbo].[Posts] SET
[Title] = #Title,dbType=NVarChar#
, [Message] = #Message,dbType=NText#
, [CreatedDate] = #CreatedDate,dbType=DateTime#
, [ModifiedDate] = #ModifiedDate,dbType=DateTime#
, [UserID] = #User.UserID,dbType=Int#
WHERE
([PostID] = #PostID,dbType=Int#)
</update>
<delete id="DeletePost" parameterClass="Post">
DELETE FROM [dbo].[Posts]
WHERE
([PostID] = #PostID,dbType=Int#)
</delete>
</statements>
</sqlMap>
