Linq to NHibernate入门示例

在微软发布C# 3.0后， LINQ在项目中发挥了重要作用。作为3.0语言身份的象征之一，学习LINQ有为重要。而NHibernate作为运用最广的ORM框架之一，在大型项目中广受开发人员的青睐。前不久，NHibernate Forge宣布NHiberante Linq 1.0正式发布了（参考）。 Linq to NHibernate有机的在NHibernate结合了Linq的查询功能，良好的把LINQ表达式转换为Criteria API。下面针对Linq to NHibernate做一个简单的Demo。

一、建立一个类名为NHibernateHelper的类

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using NHibernate;
using NHibernate.Cfg;
using System.Web;

namespace DBUtility
{
    public sealed class NHibernateHelper
    {
        private const string CurrentSessionKey = "nhibernate.current_session";
        private static readonly ISessionFactory sessionFactory;

        static NHibernateHelper()
        {
            sessionFactory = new Configuration().Configure().BuildSessionFactory();
        }

        public static ISession GetCurrentSession()
        {
            HttpContext context = HttpContext.Current;
            ISession currentSession = context.Items[CurrentSessionKey] as ISession;

            if (currentSession == null)
            {
                currentSession = sessionFactory.OpenSession();
                context.Items[CurrentSessionKey] = currentSession;
            }

            return currentSession;
        }

        public static void CloseSession()
        {
            HttpContext context = HttpContext.Current;
            ISession currentSession = context.Items[CurrentSessionKey] as ISession;

            if (currentSession == null)
            {
                // No current session
                return;
            }

            currentSession.Close();
            context.Items.Remove(CurrentSessionKey);
        }

        public static void CloseSessionFactory()
        {
            if (sessionFactory != null)
            {
                sessionFactory.Close();
            }
        }
    }

}

二、使用sql2k自带的northwind数据中的Products表为，建立Products实体和对应的Products.hbm.xml文件加上Categories和Categories.hbm.xml。

/*
Class Library : Domain
Author        : Liudong
Create Date   : 2009-10-15
*/
using System;
using System.Collections;
using System.Collections.Generic;
using System.Runtime.Serialization;

namespace Domain.Entities
{
    Products#region Products
    
    /// <summary>
    /// Entitiy:Products object for NHibernate mapped table 
    /// </summary>
    [DataContract]
    public partial class Products
    {
        ProductID#region ProductID  
    
        /// <summary>
        /// Field:ProductID 
        /// </summary>
        [DataMember]
        public virtual int? ProductID { get; set; }
        
        #endregion   
        
        ProductName#region ProductName  
    
        /// <summary>
        /// Field:ProductName 
        /// </summary>
        [DataMember]
        public virtual string ProductName { get; set; }
        
        #endregion   
        
        QuantityPerUnit#region QuantityPerUnit  
    
        /// <summary>
        /// Field:QuantityPerUnit 
        /// </summary>
        [DataMember]
        public virtual string QuantityPerUnit { get; set; }
        
        #endregion   
        
        UnitPrice#region UnitPrice  
    
        /// <summary>
        /// Field:UnitPrice 
        /// </summary>
        [DataMember]
        public virtual decimal UnitPrice { get; set; }
        
        #endregion   
        
        UnitsInStock#region UnitsInStock  
    
        /// <summary>
        /// Field:UnitsInStock 
        /// </summary>
        [DataMember]
        public virtual short UnitsInStock { get; set; }
        
        #endregion   
        
        UnitsOnOrder#region UnitsOnOrder  
    
        /// <summary>
        /// Field:UnitsOnOrder 
        /// </summary>
        [DataMember]
        public virtual short UnitsOnOrder { get; set; }
        
        #endregion   
        
        ReorderLevel#region ReorderLevel  
    
        /// <summary>
        /// Field:ReorderLevel 
        /// </summary>
        [DataMember]
        public virtual short ReorderLevel { get; set; }
        
        #endregion   
        
        Discontinued#region Discontinued  
    
        /// <summary>
        /// Field:Discontinued 
        /// </summary>
        [DataMember]
        public virtual bool Discontinued { get; set; }
        
        #endregion   
        
    
        Categories#region Categories 
        
        /// <summary>
        /// PrimaryKeyField:Categories 
        /// </summary>
        [DataMember]
        public virtual Categories CategoriesEntitiy { get; set; }
        
        #endregion
    }
    #endregion
}

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

<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" assembly="Domain" namespace="Domain.Entities">
    <class name="Domain.Entities.Products, Domain" table="Products">
        <id name="ProductID" column="ProductID" type="int" >
            <generator class="native" />
        </id>
    
        <property name="ProductName" column="ProductName" type="String" not-null="false"/>
        <property name="QuantityPerUnit" column="QuantityPerUnit" type="String" not-null="true"/>
        <property name="UnitPrice" column="UnitPrice" type="Decimal" not-null="true"/>
        <property name="UnitsInStock" column="UnitsInStock" type="Int16" not-null="true"/>
        <property name="UnitsOnOrder" column="UnitsOnOrder" type="Int16" not-null="true"/>
        <property name="ReorderLevel" column="ReorderLevel" type="Int16" not-null="true"/>
        <property name="Discontinued" column="Discontinued" type="Boolean" not-null="false"/>
    
    <many-to-one name="CategoriesEntitiy" column="CategoryID" class="Domain.Entities.Categories, Domain" />
    
    </class>
</hibernate-mapping>

/*
Class Library : Domain
Author        : Liudong
Create Date   : 2009-10-15
*/
using System;
using System.Collections;
using System.Collections.Generic;
using System.Runtime.Serialization;

namespace Domain.Entities
{
    #region Categories
    
    /// <summary>
    /// Entitiy:Categories object for NHibernate mapped table 
    /// </summary>
    [DataContract]
    public partial class Categories
    {
        #region CategoryID  
    
        /// <summary>
        /// Field:CategoryID 
        /// </summary>
        [DataMember]
        public virtual int? CategoryID { get; set; }
        
        #endregion   
        
        #region CategoryName  
    
        /// <summary>
        /// Field:CategoryName 
        /// </summary>
        [DataMember]
        public virtual string CategoryName { get; set; }
        
        #endregion   
        
        #region Description  
    
        /// <summary>
        /// Field:Description 
        /// </summary>
        [DataMember]
        public virtual string Description { get; set; }
        
        #endregion   
        
        #region Picture  
    
        /// <summary>
        /// Field:Picture 
        /// </summary>
        [DataMember]
        public virtual byte[] Picture { get; set; }
        
        #endregion   
        
    
        #region Products 
        
        /// <summary>
        /// ForeignKeyField:Products 
        /// </summary>
        [DataMember]
        public virtual IList<Products> ProductsList { get; set; }
        
        #endregion
    }
    #endregion
}

/*
Class Library : Domain
Author        : Liudong
Create Date   : 2009-10-15
*/
using System;
using System.Collections;
using System.Collections.Generic;
using System.Runtime.Serialization;

namespace Domain.Entities
{
    #region Categories
    
    /// <summary>
    /// Entitiy:Categories object for NHibernate mapped table 
    /// </summary>
    [DataContract]
    public partial class Categories
    {
        #region CategoryID  
    
        /// <summary>
        /// Field:CategoryID 
        /// </summary>
        [DataMember]
        public virtual int? CategoryID { get; set; }
        
        #endregion   
        
        #region CategoryName  
    
        /// <summary>
        /// Field:CategoryName 
        /// </summary>
        [DataMember]
        public virtual string CategoryName { get; set; }
        
        #endregion   
        
        #region Description  
    
        /// <summary>
        /// Field:Description 
        /// </summary>
        [DataMember]
        public virtual string Description { get; set; }
        
        #endregion   
        
        #region Picture  
    
        /// <summary>
        /// Field:Picture 
        /// </summary>
        [DataMember]
        public virtual byte[] Picture { get; set; }
        
        #endregion   
        
    
        #region Products 
        
        /// <summary>
        /// ForeignKeyField:Products 
        /// </summary>
        [DataMember]
        public virtual IList<Products> ProductsList { get; set; }
        
        #endregion
    }
    #endregion
}

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

<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" assembly="Domain" namespace="Domain.Entities">
    <class name="Domain.Entities.Categories, Domain" table="Categories">
        <id name="CategoryID" column="CategoryID" type="int" >
            <generator class="native" />
        </id>
        <property name="CategoryName" column="CategoryName" type="String" not-null="false"/>
        <property name="Description" column="Description" type="String" not-null="true"/>
        <property name="Picture" column="Picture" type="Byte[]" not-null="true"/>
    
    <bag name="ProductsList" inverse="true" lazy="true" cascade="all-delete-orphan">
      <key column="CategoryID" />
            <one-to-many  class="Domain.Entities.Products, Domain" />
        </bag>
    </class>
</hibernate-mapping>

三、建立数据库访问层接口(IRepository)和其实现(Repository)，随便引入程序集 (Antlr3.Runtime.dll,Castle.Core.dll,Castle.DynamicProxy2.dll,Iesi.Collections.dll,log4net.dll,NHibernate.ByteCode.Castle.dll,NHibernate.dll,NHibernate.Linq.dll)。

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace RepositoryDao
{
    public interface IRepository<T> where T : class
    {
        /// <summary>
        /// 返回IQueryable延迟加载集合
        /// </summary>
        /// <returns></returns>
        IQueryable<T> GetAll();
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

using NHibernate;
using NHibernate.Linq;

namespace RepositoryDao
{
    public class Repository<T> : IRepository<T> where T : class
    {
        public IQueryable<T> GetAll()
        {
            ISession session = DBUtility.NHibernateHelper.GetCurrentSession();
            var result=from s in session.Linq<T>() select s;
            return result;
        }
    }
}

四、建立一个ASP.NET MVC应用程序，同样引入上述的程序集。在Global.asax配置相应的MapRoute

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Mvc;
using System.Web.Routing;
using System.Text;

namespace Linq2NHibernate
{
    // Note: For instructions on enabling IIS6 or IIS7 classic mode, 
    // visit http://go.microsoft.com/?LinkId=9394801

    public class MvcApplication : System.Web.HttpApplication
    {
        public static void RegisterRoutes(RouteCollection routes)
        {
            routes.IgnoreRoute("{resource}.axd/{*pathInfo}");

            routes.MapRoute(
                "GetPage",                                              // Route name
                "page/{pageId}/{pageSize}",                           // URL with parameters
                new { controller = "Home", action = "GetPage", pageId = 1, pageSize = 10 }  // Parameter defaults
            );

            routes.MapRoute(
                "GetOrderBy",                                              // Route name
                "order",                           // URL with parameters
                new { controller = "Home", action = "GetOrderBy" }  // Parameter defaults
            );

            routes.MapRoute(
                "GetWhere",                                              // Route name
                "where/{query}",                          // URL with parameters
                new { controller = "Home", action = "GetWhere", query = "C" }  // Parameter defaults
            );

            routes.MapRoute(
                "Default",                                              // Route name
                "{controller}/{action}/{id}",                           // URL with parameters
                new { controller = "Home", action = "Index", id = "" }  // Parameter defaults
            );

        }

        protected void Application_Start()
        {
            RegisterRoutes(RouteTable.Routes);
            //log4net配置信息
            log4net.Config.XmlConfigurator.Configure();//.DOMConfigurator.Configure();
        }

        protected void Application_Error(object sender, EventArgs e)
        {
            log4net.ILog logger = log4net.LogManager.GetLogger("Logger");

            if (Server.GetLastError() != null)
            {
                Exception ex = Server.GetLastError().GetBaseException();
                StringBuilder sb = new StringBuilder();
                sb.Append(ex.Message);
                sb.Append("
SOURCE: " + ex.Source);
                sb.Append("
FORM: " + Request == null ? string.Empty : Request.Form.ToString());
                sb.Append("
QUERYSTRING: " + Request == null ? string.Empty : Request.QueryString.ToString());
                sb.Append("
引发当前异常的原因: " + ex.TargetSite);
                sb.Append("
堆栈跟踪: " + ex.StackTrace);
                logger.Error(sb.ToString());
                Server.ClearError();
            }
        }
    }
}

在Web.config中配置hibernate和log4net

<configuration>
    <configSections>
        <sectionGroup name="system.web.extensions" type="System.Web.Configuration.SystemWebExtensionsSectionGroup, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35">
            <sectionGroup name="scripting" type="System.Web.Configuration.ScriptingSectionGroup, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35">
                <section name="scriptResourceHandler" type="System.Web.Configuration.ScriptingScriptResourceHandlerSection, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" requirePermission="false" allowDefinition="MachineToApplication"/>
                <sectionGroup name="webServices" type="System.Web.Configuration.ScriptingWebServicesSectionGroup, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35">
                    <section name="jsonSerialization" type="System.Web.Configuration.ScriptingJsonSerializationSection, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" requirePermission="false" allowDefinition="Everywhere"/>
                    <section name="profileService" type="System.Web.Configuration.ScriptingProfileServiceSection, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" requirePermission="false" allowDefinition="MachineToApplication"/>
                    <section name="authenticationService" type="System.Web.Configuration.ScriptingAuthenticationServiceSection, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" requirePermission="false" allowDefinition="MachineToApplication"/>
                    <section name="roleService" type="System.Web.Configuration.ScriptingRoleServiceSection, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" requirePermission="false" allowDefinition="MachineToApplication"/>
                </sectionGroup>
            </sectionGroup>
        </sectionGroup>

    <section name="log4net" type="log4net.Config.Log4NetConfigurationSectionHandler, log4net"/>
    <sectionGroup name="common">
      <section name="logging" type="Common.Logging.ConfigurationSectionHandler, Common.Logging"/>
    </sectionGroup>
    
        <section name="hibernate-configuration" type="NHibernate.Cfg.ConfigurationSectionHandler, NHibernate"/>
    
    </configSections>
    <appSettings/>
    <connectionStrings>
        <add name="ApplicationServices" connectionString="data source=.SQLEXPRESS;Integrated Security=SSPI;AttachDBFilename=|DataDirectory|aspnetdb.mdf;User Instance=true" providerName="System.Data.SqlClient"/>
    </connectionStrings>
  
    <hibernate-configuration xmlns="urn:nhibernate-configuration-2.2">
        <session-factory name="Linq2NHibernate">
            <property name="connection.driver_class">NHibernate.Driver.SqlClientDriver</property>
            <property name="connection.connection_string">
        Server=(local);initial catalog=Northwind;Integrated Security=SSPI
      </property>
            <property name="adonet.batch_size">10</property>
            <property name="show_sql">false</property>
            <property name="dialect">NHibernate.Dialect.MsSql2000Dialect</property>
            <property name="use_outer_join">true</property>
            <property name="command_timeout">60</property>
            <property name="query.substitutions">true 1, false 0, yes 'Y', no 'N'</property>
            <!--2.1要配置延迟加载的代理 这里配置为Castle -->
            <property name="proxyfactory.factory_class">NHibernate.ByteCode.Castle.ProxyFactoryFactory, NHibernate.ByteCode.Castle</property>
            <!--实体xml隐射文件的程序集-->
            <mapping assembly="Domain"/>
        </session-factory>
    </hibernate-configuration>

  <log4net debug="true">
    <appender name="LogFileAppender" type="log4net.Appender.FileAppender">
      <param name="File" value="LogsApplication.log.txt"/>
      <param name="datePattern" value="MM-dd HH:mm"/>
      <param name="AppendToFile" value="true"/>
      <layout type="log4net.Layout.PatternLayout">
        <param name="ConversionPattern" value="%d [%t] %-5p %c [%x] - %m%n"/>
      </layout>
    </appender>
    <appender name="HttpTraceAppender" type="log4net.Appender.ASPNetTraceAppender">
      <layout type="log4net.Layout.PatternLayout">
        <param name="ConversionPattern" value="%d [%t] %-5p %c [%x] - %m%n"/>
      </layout>
    </appender>
    <appender name="EventLogAppender" type="log4net.Appender.EventLogAppender">
      <layout type="log4net.Layout.PatternLayout">
        <param name="ConversionPattern" value="%d [%t] %-5p %c [%x] - %m%n"/>
      </layout>
    </appender>
    <appender name="RollingLogFileAppender" type="log4net.Appender.RollingFileAppender">
      <param name="File" value="Logs/Log.txt"/>
      <param name="AppendToFile" value="true"/>
      <param name="MaxSizeRollBackups" value="10"/>
      <param name="MaximumFileSize" value="100K"/>
      <param name="RollingStyle" value="Size"/>
      <param name="StaticLogFileName" value="true"/>
      <layout type="log4net.Layout.PatternLayout">
        <param name="ConversionPattern" value="%d [%t] %-5p %c [%x] - %m%n"/>
      </layout>
    </appender>
    <root>
      <level value="ALL"/>
      <appender-ref ref="RollingLogFileAppender"/>
    </root>
  </log4net>
  
    <system.web>

在HomeController加入如下方法

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Mvc;
using Domain.Entities;
using RepositoryDao;

namespace Linq2NHibernate.Controllers
{
    [HandleError]
    public class HomeController : Controller
    {
        public ActionResult Index()
        {
            ViewData["Message"] = "Welcome to ASP.NET MVC!";

            return View();
        }

        public ActionResult About()
        {
            return View();
        }

        /// <summary>
        /// 获取所有
        /// </summary>
        /// <returns></returns>
        public ActionResult GetAll()
        {
            IRepository<Products> dao = new Repository<Products>();
            var products = dao.GetAll();
            
            ViewData["List"] = products;
            return View();
        }

        /// <summary>