In this article we will see that how you can create mapping between different classes using NHibernate.



I know you all must be really anxious to find out that how NHibernate works and how it can make your life easier. In this article we will look at the add feature of the NHibernate. I will go step by step so you understand what is going on.

Making a Class Library:

The first task is to create a class library which will be mapped using the NHibernate. So, lets make a simple class User.

public class User


private int personID;

private string email;

private string password;

private bool status;

private DateTime dateCreated;


// Defining properties

public int PersonID


get { return personID; }

set { personID = value; }


public string Email


get { return email; }

set { email = value; }


public string Password


get { return password; }

set { password = value; }



public bool Status


get { return status; }

set { status = value; }


public DateTime DateCreated


get { return dateCreated; }

set { dateCreated = value; }



As you can see that there is nothing special about the class. It has some private variables which you can access using the properties. All of this has been explained in my articles before.


All these properties will map to the database fields. That's why I have created the database script file for you. Just run the script file using query analyzer and it will create table for you. If it does not work than you can easily create a table based on the properties above.

Creating Mapping File:

Now let's take a look at the mapping file for the User.cs class. This mapping file is called (User.hbm.xml). It's a good idea to name the mapping file based on the class name.

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

<hibernate-mapping xmlns="urn:nhibernate-mapping-2.0">

<class name="Glasses.Test.User, Glasses" table="Person">

<id name="PersonID" column="PersonID" type="Int32" length="4" unsaved-value="0">

<generator class="identity" />


<property name="Email" column= "Email" type="String" length="50"/>

<property name="Password" type="String" length="50"/>

<property name="Status" type="Boolean" length="1"/>

<property name="DateCreated" type="DateTime"/>



Let's take a look at the mapping file now.



Make sure that the mapping file is configured as the "Embedded Resource". Right click on the "User.hbm.xml" file and select properties and set build option to "Embedded Resource".

Add Method Code:

Now let's see the Add method that adds the user object into the database. In future articles we will implement an interface and inherit from that interface to get the common functionality. But for now let's look at the easy way to add the object.

public static void Add(User user)

{// make the configuration file

Configuration cfg = new Configuration();


ISessionFactory factory = cfg.BuildSessionFactory();

ISession session = factory.OpenSession();

ITransaction transaction = session.BeginTransaction();






The Client Code:

The Client code is pretty simple and self explanatory.

private void Button1_Click(object sender, System.EventArgs e)


User user = new User();

user.Email = "";

user.Password = "mypassword";

user.Status = true;

user.DateCreated = DateTime.Now;




Don't wait now and check your database. A new entry should be added if you have done everything right. Isn't this the coolest thing ever. In the upcoming articles we will see more features of NHibernate.

I hope you enjoyed the article. Happy programming !