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Using Nhibernate in VB.NET

S.SRIVATHSAN

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7 Jan 2008

Implementation Nhibernate concept in VB.NET

Introduction

This article is about how to implement Nhibernate in VB.NET.

Background

Refer to www.hibernate.org to learn what Nhibernate is all about. I use VB 2005 with the backend as PostGres.

Using the Code

It requires Nhibernate.dll files. Download and install Nhibernate files from the above link or search for it in Google.

Create a VB.NET Project - WindowsApplication1
Add a form, place 3 labels and textboxes{eno, ename, salary}, 1 button for save.
Import the following things by adding reference. Right Click in WindowsApplication1. (Don't change the name of the project now).
In the “Add Reference” dialog box, the files to be referred(imported) are:
- Iesi.Collections.dll
- log4net.dll
- Mono.Security.dll
- Npgsql.dll --- this is for PostGres Users
- Nhibernate.dll
- System.Data.Sqlxml
Create a table named testcust in the database. {eno integer, ename varchar2(15), salary integer}. Set Primary key for eno in the table.

Add a class file in the project by “AddNew Item”. Rename or Save it as “testcust.vb”.

CODING for the Class file is as follows:

Imports NHibernate
    Imports NHibernate.Cfg
    Imports log4net
    Imports System.Configuration

    Public Class testcust

            Private enumber As Int32
            Private sal As Int32
            Private empname As String

        Public Overridable Property eno() As Int32
    
            Get
                    Return enumber
            End Get

            Set(ByVal value As Int32)
                enumber = value
            End Set
        End Property

        Public Overridable Property ename() As String
            Get
                Return empname
            End Get
    
            Set(ByVal value As String)
                empname = value
            End Set
        End Property

        Public Overridable Property salary() As Int32
            Get
                Return sal
            End Get

            Set(ByVal value As Int32)
                sal = value
            End Set
        End Property

    End Class

Right click in the WindowsApplication1 -- “Add New Item” -- “Text File”
Rename it as “app.config” and press enter

In the app.config, write the code below:
(It is here for database connection I used postgresql.)

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

    <configSections>
        <section name="nhibernate"
          type="System.Configuration.NameValueSectionHandler, System, 
         Version=1.0.5000.0,Culture=neutral, PublicKeyToken=b77a5c561934e089"
    />
        <section name="log4net"
          type="log4net.Config.Log4NetConfigurationSectionHandler, log4net"
    />
    </configSections>

    <log4net>
        <appender name="rollingFile" 
		type="log4net.Appender.RollingFileAppender, log4net" >
            <param name="File" value="log.txt" />
            <param name="AppendToFile" value="true" />
            <param name="RollingStyle" value="Date" />
            <param name="DatePattern" value="yyyy.MM.dd" />
            <param name="StaticLogFileName" value="true" />
            <layout type="log4net.Layout.PatternLayout, log4net">
                <param name="ConversionPattern" 
		value="%d [%t] %-5p %c [%x] &lt;%X{auth}&gt; - %m%n" />
            </layout>
        </appender>
        <logger name ="MyApp">
            <level value="DEBUG"/>
            <appender-ref ref="rollingFile"/>
        </logger>
        <!--<root>
            <priority value="DEBUG" />
            <appender-ref ref="rollingFile" />
        </root>-->
    </log4net>

    
    <nhibernate>
        <add
          key="hibernate.connection.provider"          
          value="NHibernate.Connection.DriverConnectionProvider"
    />
        <add
          key="hibernate.dialect"                      
          value="NHibernate.Dialect.PostgreSQLDialect"
    />
        <add
          key="hibernate.connection.driver_class"          
          value="NHibernate.Driver.NpgsqlDriver"
    />
        <add
          key="hibernate.connection.connection_string"
          value="Server=10.3.2.1;Database=GBDEVEL;User Name=erpdotnet;Password=erp"
    />
    </nhibernate>

</configuration>

If you are using MSSQL 2000, the app.config coding is as below:

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
    <configSections>
        <section
          name="nhibernate" 
          type="System.Configuration.NameValueSectionHandler,System, 
	   Version=1.0.5000.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" 
    />
    </configSections>

    <nhibernate>
        <add 
          key="hibernate.connection.provider"
          value="NHibernate.Connection.DriverConnectionProvider"
    />
        <add
          key="hibernate.dialect"
          value="NHibernate.Dialect.MsSql2000Dialect"
    />
        <add
          key="hibernate.connection.driver_class"
          value="NHibernate.Driver.SqlClientDriver"
    />
        <add
          key="hibernate.connection.connection_string"
          value="Server=localhost;
		initial catalog=nhibernate;Integrated Security=SSPI"
    />
    </nhibernate>
</configuration>

Note: Change the user name, password, server name as suitable to you.

In the Form1, add 3 labels and textboxes to enter eno, ename, salary and a button to save. The coding is as follows:

Imports NHibernate
Imports NHibernate.Cfg
Imports log4net
Imports System.Configuration
Imports NHibernate.Connection
Imports Iesi.Collections

Public Class Form1

    Private Sub Button1_Click(ByVal sender As System.Object, _
	ByVal e As System.EventArgs) Handles Button1.Click

        Dim myConfig As New Configuration
        myConfig.AddAssembly("WindowsApplication1")
        myConfig.SetProperty("hibernate.dialect", _
		"NHibernate.Dialect.PostgreSQLDialect")

        'Dim myFactory As ISessionFactory = myConfig.Configure.BuildSessionFactory
        Dim myFactory As ISessionFactory = myConfig.BuildSessionFactory

        Dim mySession As ISession = myFactory.OpenSession

        Dim myTransaction As ITransaction = mySession.BeginTransaction

        Dim cust As New testcust
        cust.eno = TextBox1.Text
        cust.ename = TextBox2.Text
        cust.salary = TextBox3.Text

        mySession.Save(cust)
        myTransaction.Commit()
        mySession.Close()

        MsgBox("success")

    End Sub
End Class

Likewise as the class file, open a text file and rename it as “testcust.hbm.xml”. The coding for this is:
```
<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2">
    <class name="WindowsApplication1.testcust, 
	WindowsApplication1" table="erp.testcust">
        <id name="eno" column="eno" type="Int32">
            <generator class="assigned" />
        </id>
        <property name="ename" column="ename" type="String" length="15" />

        <property name="salary" column="salary" type="Int32" length="12" />
    </class>
</hibernate-mapping>
```
Note: Make sure with the data type used in the table in database, class file and the property name here used are case-sensitive. For example: salary defined in class file or database must have the same name here. Salary is itself wrong. You may get ADOException Unhandled or Column Mismatch Exception. Mention the database table name correctly, if you used it with schema. The <generator class = “assigned”> or <generator class = “identity”> can be used. Both may have different effects based on the constraints you set to the attributes.
Make sure that “testcust.hbm.xml” file's property of Build Action is selected as Embedded Resources (default is none or compile). You may get Mapping Exception of entity or class due to this, if not selected.
Save this VB.NET Project properly and Run it.

You can also use “hibernate.cfg.xml” instead of “app.config”. The coding for that is:

<?xml version='1.0' encoding='utf-8'?>
<hibernate-configuration xmlns="urn:nhibernate-configuration-2.2">

    <!-- an ISessionFactory instance -->

    <session-factory>

        <!-- properties -->

        <property name="connection.provider">
            NHibernate.Connection.DriverConnectionProvider

        </property>

        <property name="connection.driver_class">
            NHibernate.Driver.NpgsqlDriver

        </property>

        <property name="connection.connection_string">
		Server=10.3.2.1;Database=GBDEVEL;User Name=erpdotnet;
		Password=erp</property>

        <property name="show_sql">false</property>

        <property name="dialect">NHibernate.Dialect.PostgreSQLDialect</property>

        <property name="use_outer_join">true</property>

        <!-- mapping files -->

        <mapping resource="WindowsApplication1.testcust.hbm.xml" 
		assembly="WindowsApplication1" />

    </session-factory>

</hibernate-configuration>

Note: If you are using app.config, don't write hibernate.cfg.xml. If you are using this, don't use app.config.

For MSSQL2000, use this for the property tag:

  <property name="connection.provider">
	NHibernate.Connection.DriverConnectionProvider
</property>

<property name="connection.driver_class">NHibernate.Driver.SqlClientDriver
</property>

<property name="connection.connection_string">
	Server=(local);initial catalog=AdventureWorks;User Id=sa;
	Password=woozelwazzel</property>

<property name="show_sql">false</property>

<property name="dialect"> NHibernate.Dialect.MsSql2000Dialect </property>

<property name="use_outer_join">true</property>

Note: Change the username, password, server name as suitable for you.

Make sure you import and connect everything properly and change the properties of BuildAction -- Embedded Resources of “testcust.hbm.xml”. You may get ADO EXCEPTIONS, if not!!!!!
Enjoy the coding.

You can also use VB.NET 2005.

Points of Interest

Learn how some exceptions occur and why and how to solve that.

History

7^th January, 2008: Initial post

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