I Made Krisna's Times My Way to Write the Times

NHibernate for MySQL C# Source Code

Now we're going to make a database connection using ORM Framework that was discussed before, NHibernate.

What the requirement of using NHibernate for our projects? First, add some reference like i've explained on previous post (Using NHibernate ORM for .NET Framework), NHibernate.dll, NHibernate.ByteCode.LinFu.dll, and MySql.Data.dll

Second step, create the app.config file and this step also have been explained on my previous post. And for this project the app.config content is :

<?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.MySQL5Dialect</property>
      <property name="connection.provider">NHibernate.Connection.DriverConnectionProvider</property>
      <property name="connection.connection_string">server=127.0.0.1;User Id=nhibernate;password=nhibernate;Persist Security Info=True;database=nhibernate</property>
      <property name="proxyfactory.factory_class">NHibernate.ByteCode.LinFu.ProxyFactoryFactory, NHibernate.ByteCode.LinFu</property>
      <mapping assembly="SimpleNHibernate"/>
    </session-factory>
  </hibernate-configuration>
</configuration>

Then the most important step, creating a persistant class that representing the database table. Suppose my database just have 1 table, user and the structure like this :

namespace SimpleNHibernate
{
    class User
    {
        private int userId;
        private string userName;

        public User() { }

        public virtual int UserId
        {
            set { this.userId = value; }
            get { return this.userId; }
        }

        public virtual string UserName
        {
            set { this.userName = value; }
            get { return this.userName; }
        }

    }
}

The important thing to remember is make the property "public virtual" because that NHibernate need

And the second important step, create a mapping xml which tells NHibernate how to make relation between persistent objects with relational database table. Now, create a xml file named user.hbm.xml then change the Build Action propery to "Embedded Resource" and the content like this :

<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" namespace="SimpleNHibernate" assembly="SimpleNHibernate">
  <class name="User" table="user">
    <id name="UserId">
      <column name="user_id" sql-type="int(32)" not-null="true" />
      <generator class="increment" />
    </id>
    <property name="UserName">
      <column name="user_name" sql-type="varchar(128)" not-null="true" />
    </property>
  </class>
</hibernate-mapping>

For primary key we use <id> and the other column we use <property>. And inside those tag there is <column> tag that's the mapping for the <id> or <property> attribute from persistant class to the databasae column. And for auto_increment function from MySQL Database use <generator class="increment" /> on the id.

Okay the persistant class and it's mapping done now, next step is creating a helper class or connector class to make our job easier. This step is optional if you're prefer to use NHibernate directly and repeat some code. And here's my code for creating the helper class.

using NHibernate;
using NHibernate.Cfg;

namespace SimpleNHibernate
{
    class NHibernateConnector
    {
        private ISessionFactory sessionFactory;
        private ITransaction transaction;
        private ISession session;

        public NHibernateConnector()
        {
            this.sessionFactory = new Configuration().Configure().BuildSessionFactory();
        }

        public void OpenConnection()
        {
            this.session = sessionFactory.OpenSession();
            this.transaction = this.session.BeginTransaction();
        }

        public void CloseConnection()
        {
            this.session.Close();
        }

        public void Commit()
        {
            this.transaction.Commit();
        }

        public void Rollback()
        {
            this.transaction.Rollback();
        }

        public IQuery CreateQuery(string hql)
        {
            return this.session.CreateQuery(hql);
        }

        public ISession Session
        {
            get { return this.session; }
        }

        public ITransaction Transaction
        {
            get { return this.transaction; }
        }

    }
}

The preparation step is done.. now look at the example for inserting data to the MySQL DBMS using NHibernate Framework.

namespace SimpleNHibernate
{
    class Program
    {
        static void Main(string[] args)
        {
            NHibernateConnector conn = new NHibernateConnector();
            conn.OpenConnection();

            User imKrisna = new User();
            imKrisna.UserName = "I Made Krisna Widhiastra";

            conn.Session.Save(imKrisna);

            conn.Commit();
            conn.CloseConnection();
        }
    }
}