NHibernate自定义数据类型
有时候在NHibernate中的基本数据类型可能不够好用，可以考虑自定义一个数据类型。
可以通过实现IUserType或者ICompositeUserType接口来实现这一功能。 ICompositeUserType较IUserType而言可以提供更多的控制。一般情况我们实现IUserType即可。
IUserType Members
Public Instance Properties
 IsMutable |
Are objects of this type mutable? |
| ReturnedType |
The type returned by NullSafeGet() |
| SqlTypes |
The SQL types for the columns mapped by this type. |
Public Instance Methods
 DeepCopy |
Return a deep copy of the persistent state, stopping at entities and at collections. |
| Equals |
Compare two instances of the class mapped by this type for persistent "equality" ie. equality of persistent state |
| NullSafeGet |
Retrieve an instance of the mapped class from a JDBC resultset. Implementors should handle possibility of null values. |
| NullSafeSet |
Write an instance of the mapped class to a prepared statement. Implementors should handle possibility of null values. A multi-column type should be written to parameters starting from index. |
比如：我想实现在数据库里存储格式为“数据；数据；数据”，而在类中体现为IList。这样我们可以减少一些一对多的映射。我们可以用它来存放EMail等数据。
自定义数据类：
using System;
using System.Collections;
using System.Data;
using System.Text;
using NHibernate;
using NHibernate.SqlTypes;
namespace Index.Data.NHibernateHelper
{
/// <summary>
/// 自定义的NH数据类型，使用；分隔存储多个数据
/// </summary>
public class DDLList : IUserType
{
private static readonly char SPLITTER = ';';
private static readonly SqlType[] TYPES = new SqlType[] {NHibernateUtil.String.SqlType};
IUserType 成员
/// <summary>
/// 将string拼装成一个字符串，以“；”分隔
/// </summary>
/// <param name="list"></param>
/// <returns></returns>
private string ListToString(IList list)
{
if (list.Count == 0)
{
return null;
}
StringBuilder sb = new StringBuilder();
for (int i = 0; i < list.Count - 1; i++)
{
sb.Append(list[i]).Append(SPLITTER);
}
sb.Append(list[list.Count - 1]);
return sb.ToString();
}
/// <summary>
/// 将“；”分隔的字符串解析为数组
/// </summary>
/// <param name="value"></param>
/// <returns></returns>
private IList StringToList(string value)
{
string[] strs = value.Split(SPLITTER);
IList emailList = new ArrayList();
for (int i = 0; i < strs.Length; i++)
{
emailList.Add(strs[i]);
}
return emailList;
}
}
}
using System.Collections;
using System.Data;
using System.Text;
using NHibernate;
using NHibernate.SqlTypes;
namespace Index.Data.NHibernateHelper
{
/// <summary>
/// 自定义的NH数据类型，使用；分隔存储多个数据
/// </summary>
public class DDLList : IUserType
{
private static readonly char SPLITTER = ';';
private static readonly SqlType[] TYPES = new SqlType[] {NHibernateUtil.String.SqlType};
IUserType 成员
/// <summary>
/// 将string拼装成一个字符串，以“；”分隔
/// </summary>
/// <param name="list"></param>
/// <returns></returns>
private string ListToString(IList list)
{
if (list.Count == 0)
{
return null;
}
StringBuilder sb = new StringBuilder();
for (int i = 0; i < list.Count - 1; i++)
{
sb.Append(list[i]).Append(SPLITTER);
}
sb.Append(list[list.Count - 1]);
return sb.ToString();
}
/// <summary>
/// 将“；”分隔的字符串解析为数组
/// </summary>
/// <param name="value"></param>
/// <returns></returns>
private IList StringToList(string value)
{
string[] strs = value.Split(SPLITTER);
IList emailList = new ArrayList();
for (int i = 0; i < strs.Length; i++)
{
emailList.Add(strs[i]);
}
return emailList;
}
}
}
在映射文件中如此设置
<property name="Email1" type="Index.Data.NHibernateHelper.DDLList,Index.Data.NHibernateHelper" column="Email1" />
在实体类中直接使用IList映射即可。
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