NHibernate Example Code in C#.Net


Information
In this article, i will create a simple application that which implements NHibernate, in database side, i will use SQL Server 2008. What is NHibernate ? I will not explain it in there,  there are lot of explanations in the internet, like in here.
You can download latest NHibernate version here.
First, i will create a simple database that have just one table (and i added some record in there):
This is the DDL (Data Definition Language)






create table ACCOUNT (
   ACCID                int         identity(1,1)       not null,
   USERNAME             varchar(50)                     null,
   PASS                 varchar(50)                     null,
   constraint PK_ACCOUNT primary key nonclustered (ACCID)

Hmm.. what does this Identity(1,1)  mean ??? It is mean we will set ACCID attribute, the primary key, to become autonumbered, the value will be added automatically incrementing from 1, 2, 3, … and so on.
Next step, we will create simple solution in Visual Studio 2008 SP1 (remember … to connect to SQL Server 2008, your Visual Studio 2008 must be Service Pack 1 ).

Add some references
  1. NHibernate.dll (NHibernate library)
  2. NHibernate.ByteCode.LinFu.dll (for lazy loading)
  3. System.configuration


Test your connection with database using Server Explorer


Do not forget to copy the connection string…

For my example, my database connection string is :  ]
Data Source=WIRTH;Initial Catalog=TestNHibernate;User ID=azer89;Password=azer89
Next,  create an App.config file in your project (Just Right click your project, Add, New Item, and Application Configuration File)

Set your App.config like this :
















<?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="connection.provider">NHibernate.Connection.DriverConnectionProvider</property>
      <property name="connection.driver_class">NHibernate.Driver.SqlClientDriver</property>
      <property name="connection.connection_string">Data Source=WIRTH;Initial Catalog=TestNHibernate;User ID=azer89;Password=azer89</property>
      <property name="dialect">NHibernate.Dialect.MsSql2008Dialect</property>
      <property name="proxyfactory.factory_class">NHibernate.ByteCode.LinFu.ProxyFactoryFactory, NHibernate.ByteCode.LinFu</property>
      <mapping assembly="NHibernateTest"/>
    </session-factory>
  </hibernate-configuration>
</configuration>
You must pay attention in property connection.connection_string and dialect in code above. Add a model class similar to Account Table, the fields should be similar too

Your Account.cs should be like this :































using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
 
namespace NHibernateTest
{
    class Account
    {
        private int accId;
        private string username;
        private string pass;
 
        public virtual int AccId
        {
            get { return accId; }
            set { accId = value; }
        }
 
        public virtual string UserName
        {
            get { return username; }
            set { username = value; }
        }
 
        public virtual string Pass
        {
            get { return pass; }
            set { pass = value; }
        }
    }
}
After creating Account class, we will create map to Account Table using XML file, so NHibernate will know that Account class in application will map to Account Table in database. The XML filename will be “Account.nbm.xml”















<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" namespace="NHibernateTest" assembly="NHibernateTest">
  <class name="Account" table="ACCOUNT" lazy="false">
    <id name="AccId">
      <column name="ACCID"/>
      <generator class="native"/>
    </id>
    <property name="UserName">
      <column name="username"/>
    </property>
    <property name="Pass">
      <column name="pass"/>
    </property>
  </class>
</hibernate-mapping>
Look at generator class, the value is “native”, it is because we have set ACCID column to autoincrement. Oh yeah, Build Action for hbm.xml file must be “Embedded Resource”

Next step is to create persistence class, we will name it NHibernateHelper.cs
































using System.Reflection;
using NHibernate;
using NHibernate.Cfg;
 
namespace NHibernateTest
{
    public sealed class NHibernateHelper
    {
        private static ISessionFactory SessionFactory;
 
        private static void OpenSession()
        {
            Configuration configuration = new Configuration();
            configuration.AddAssembly(Assembly.GetCallingAssembly());
            SessionFactory = configuration.BuildSessionFactory();
        }
 
        public static ISession GetCurrentSession()
        {
            if (SessionFactory == null)
                NHibernateHelper.OpenSession();
 
            return SessionFactory.OpenSession();
        }
 
        public static void CloseSessionFactory()
        {
            if (SessionFactory != null)
                SessionFactory.Close();
        }
    }
}
Since ISessionFactory is expensive to be created (it almost take one second in my old computer) we will create one object of ISessionFactory, otherwise with ISession, very cheap to be created, so we can create it very often in your application. We will test the code :































using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using NHibernate;
 
namespace NHibernateTest
{
    class Program
    {
        static void Main(string[] args)
        {
            string username = "reza";
            string pass = "reza";
 
            ISession session = NHibernateHelper.GetCurrentSession();
            IQuery query = session.CreateQuery("FROM Account WHERE username = :name  AND pass = :pass ");
            query.SetString("name", username);
            query.SetString("pass", pass);
            IList<Account> acc = query.List<Account>();
            session.Close();
            if (acc.Count == 0)
                Console.WriteLine("Cannot find specified user");
            else
                Console.WriteLine("Found " + acc[0].UserName);
 
            Console.ReadKey();
 
        }
    }
}
It works ! Fine

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