NHibernate入門

Question

我想在NHibernate中開發我的Hello World程序。

我的代碼如下：

MyClass.cs 
---------- 
using System.Collections.Generic; 
using System.Text; 
using System; 
using NHibernate.Collection; 
using NHibernate.Mapping; 
using Iesi.Collections; 

namespace NHibernate__MyClass 
{ 
    public class MyClass 
    { 
     int id; 
     string name; 
     int _value; 

     public MyClass() 
     { 
      id = 0; 
      name = ""; 
      _value = 0; 
     } 

     public virtual int Id 
     { 
      get { return id; } 
      set { id= value; } 
     } 

     public virtual string Name 
     { 
      get { return name; } 
      set { name= value; } 
     } 

     public virtual int Value 
     { 
      get { return _value; } 
      set { _value= value; } 
     } 
    } 
} 


MyClass.hbm.xml 
--------------- 
<?xml version="1.0" encoding="utf-8" ?> 

<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" namespace="NHibernate__MyClass" assembly="NHibernate__MyClass"> 
    <class name="MyClass" table="MyClass"> 
    <id name="Id"> 
     <column name="ID" sql-type="int" not-null="true"/> 
     <generator class="native" /> 
    </id> 
    <property name="Name"> 
     <column name="Name" not-null="true" /> 
    </property> 
    <property name="Value"> 
     <column name="Value" not-null="true" /> 
    </property> 
    </class> 
</hibernate-mapping> 

Program.cs 
---------- 
using System; 
using System.Collections.Generic; 
using System.Text; 

using NHibernate; 
using NHibernate.Cfg; 

namespace NHibernate__MyClass 
{ 
    class Program 
    { 
     static void Main(string[] args) 
     { 
      MyClass myClass = new MyClass(); 
      myClass.Id = 1; 
      myClass.Name = "Hello World!"; 
      myClass.Value = 100; 

      ISessionFactory sessionFactory = new Configuration().Configure().BuildSessionFactory(); 
      ISession session = sessionFactory.OpenSession(); 

      session.BeginTransaction(); 
      session.Save(myClass); 
      session.Transaction.Commit(); 

      Console.ReadLine(); 
     } 
    } 
} 

App.config 
---------- 
<?xml version="1.0" encoding="utf-8" ?> 
<configuration> 
    <configSections> 
    <section 
    name="hibernate-configuration" 
    type="NHibernate.Cfg.ConfigurationSectionHandler, NHibernate" 
/> 
    </configSections> 

    <hibernate-configuration xmlns="urn:nhibernate-configuration-2.2"> 
    <session-factory> 
     <property name="dialect">NHibernate.Dialect.MsSql2000Dialect</property> 
     <property name="connection.provider">NHibernate.Connection.DriverConnectionProvider</property> 
     <property name="connection.connection_string">Data Source=.\SQLEXPRESS;Initial Catalog=NHibernate;Integrated Security=True</property> 
     <mapping assembly="NHibernate__MyClass" /> 
    </session-factory> 
    </hibernate-configuration> 
</configuration> 


SQL Table 
--------- 
CREATE TABLE [dbo].[MyClass](
    [ID] [int] NOT NULL, 
    [Name] [varchar](50) NOT NULL, 
    [value] [int] NOT NULL 
) ON [PRIMARY] 

但是該程序產生一異常：

異常消息：{「無法插入：[NHibernate__MyClass.MyClass] [SQL：INSERT INTO MyClass的（名稱，值）VALUES（？，？）;選擇SCOPE_IDENTITY（）]「}

內部異常消息：{」不能將值NULL插入'ID'列'NHibernate.dbo.MyClass';列不允許爲空，INSERT失敗。\ r \ n聲明已終止。「}

可能是什麼問題？

NHibernate的DLL版本= 2.0.0.2002

Answer 1

因爲在你的映射文件

<generator class="native" /> 

在SQL這個標籤，你需要在該表中設置ID字段來標識。

你也可以讓nHibernate生成標識字段。