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Monday, 11 June 2012

Developing an ASP.NET page with MasterPage and Localization

Introduction

While seeking on the internet for a solution to implement localization within an ASP.NET application using a MasterPage, I realized that a lot of people have got the same problem to solve. Unfortunately, I could not find a suitable solution thus, I intended to do my own implementation.

Background

The solution presented within this article uses the standard localization mechanism of the .NET framework.

Using the code

The published solution uses the Session object as storage for the currently selected culture. This will be initialized during the Session_Start method that is part of the global.asax file.
If a culture change is requested by the user, the MasterPage changes the stored culture in the Session object.
In a BasePage that inherits from Page, the method InitializeCulture is overridden and sets the appropriate culture information stored in the Session object to the current thread. Therefore, every Web Form needs to derive from this BasePage.
Let's start with the Global.asax file:
void Session_Start(object sender, EventArgs e) 
{
    //set english as default startup language
    Session["MyCulture"] = "en-GB";
}
Alternatively, the culture can be defined in the Web.config file with the key <globalization culture="en-GB" /> and then be processed and stored in the Session object from the Session_Start method.
The next step is the master page:
<%@ Master Language="C#" AutoEventWireup="true" 
           CodeFile="MasterPage.master.cs" Inherits="MasterPage" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" 
         "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
    <title>[Smart-Soft - Masterpage with Localization Support]</title>
</head>

<body>
    <form id="theForm" runat="server">
    <div>
        <asp:contentplaceholder id="ContentPlaceHolder" runat="server">
        </asp:contentplaceholder>
    </div>
    <div style="margin-top:20px;">
        <asp:LinkButton ID="btnSetGerman" runat="server" Text="Deutsch" 
           CommandArgument="de-CH" OnClick="RequestLanguageChange_Click">
        </asp:LinkButton>  
        <asp:LinkButton ID="btnSetEnglish" runat="server" Text="English" 
           CommandArgument="en-GB" OnClick="RequestLanguageChange_Click">
        </asp:LinkButton>
    </div>
    </form>
</body>
</html>
The buttons to change the culture can be either placed in the MasterPage directly, or in any embeddedUserControl. In order to determine the requested language, the CommandArgument attribute of the LinkButtonis used.
..And the code-behind of the master page:
public partial class MasterPage : System.Web.UI.MasterPage
{
    protected void Page_Load(object sender, EventArgs e)
    {
    }

    protected void RequestLanguageChange_Click(object sender, EventArgs e)
    {
        LinkButton senderLink = sender as LinkButton;

        //store requested language as new culture in the session
        Session["MyCulture"] = senderLink.CommandArgument;

        //reload last requested page with new culture
        Server.Transfer(Request.Path);
    }
}
The requested language, passed within the CommandArgument, is processed and stored in the Session object. Afterwards, the initially requested page will be reloaded on the server side.
Last but not least, the BasePage:
/// <summary>
/// Custom base page used for all web forms.
/// </summary>
public class BasePage : Page
{
    private const string m_DefaultCulture = "en-GB";
    
    protected override void InitializeCulture()
    {
        //retrieve culture information from session
        string culture = Convert.ToString(Session["MyCulture"]);

        //check whether a culture is stored in the session
        if (!string.IsNullOrEmpty(culture)) Culture = culture;
        else Culture = m_DefaultCulture;

        //set culture to current thread
        Thread.CurrentThread.CurrentCulture = CultureInfo.CreateSpecificCulture(culture);
        Thread.CurrentThread.CurrentUICulture = new CultureInfo(culture);

        //call base class
        base.InitializeCulture();
    }
}
As mentioned above, the InitializeCulture method is overridden, and gets the stored culture from the Sessionobject and assigns it to the currently running thread.


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