I'm not sure if I should post this here.  What I want to do involves some new localization features provided by ASP.NET 2.0.  But my problem is quite generic even for ASP.NET 1.x.  In a shor word, where can I set/change the page's culture prior to FrameworkInitialize()?


I am using ASP.NET 2.0 Beta 2.  I want to toggle the page between two languages by clicking a toggle button on the page.  In the button's click event handler, I will toggle the language which is saved inside a session variable.  I try to render the page using the new language, but it does not work.

I have read three articles about the improved localization for ASP.NET 2.0, and the page lifecycle/pipeline.  They are listed at the end of this post.


From article 1 - section "Implicit Localization Expressions", I know that the localized content of the page is decided by the following code invoked inside FrameworkInitlize().

    button1.Text = ((string)
      base.GetLocalResourceObject("LinkButtonResource1.Text"));

Then I think I should set the page's culture before the execution of FrameworkInitlize().  But I'm not sure of the exact place in the page lifecycle.


In article 2 - section "Page Lifecycle", there are a list of Page Lifecycle methods.  The following is a partial list at the beginning of the lifecycle that I think are relevant with my problem.

    Constructor
    Construct
    TestDeviceFilter
    AddParsedSubObject
    DeterminePostBackMode
    OnPreInit
    LoadPersonalizationData
    InitializeThemes
    OnInit


In article 3 - section "The Page Lifecycle", it says:

Once the HTTP page handler class is fully identified, the ASP.NET run time calls the handler's ProcessRequest method to process the request. ... (it) begins by calling the method FrameworkInitialize, which builds the controls tree for the page. The method is a protected and virtual member of the TemplateControl class - the class from which Page itself derives. Any dynamically generated handler for an .aspx resource overrides FrameworkInitialize. In this method, the whole control tree for the page is built.

Next, ProcessRequest makes the page transit various phases: initialization, loading of view state information and postback data, loading of the page's user code and execution of postback server-side events. After that, the page enters in rendering mode: the updated view state is collected; the HTML code is generated and then sent to the output console. Finally, the page is unloaded and the request is considered completely served.


From this, I deduce that the method FrameworkInitlize() is called at least prior to OnPreInit().  But I do not know where its exact position is in the lifecycle.

Anyway, I tried the following.

I override the method Construct to toggle the current thread's culture, as shown below.  But it does not work.  The displayed page is still in the browser's language.

    protected override void Construct()
    {
        base.Construct();

        string l;
        if(Thread.CurrentThread.CurrentUICulture.Name == "en-US")
        {
            l = "zh-CN";
        }
        else
        {
            l = "en-US";
        }
        CultureInfo ci = CultureInfo.CreateSpecificCulture(l);
        Thread.CurrentThread.CurrentCulture = ci;
        Thread.CurrentThread.CurrentUICulture = ci;
    }

I also tried to overried OnInit() and OnPreInit() to set the page's culture, but it is still futile.

    protected override void OnInit(EventArgs e)
    {
        base.OnInit(e);

        Page.Culture = Language;
    }

I'll be greatly appreciated if anyone can provide any explanation/suggestions/workarounds to my problem?  Thanks a lot in advance!


Reference:
Articles 1. ASP.NET 2.0 Localization Features: A Fresh Approach to Localizing Web Applications
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dnvs05/html/ASP2local.asp

Articles 2. ASP.NET 2.0 Internals
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dnvs05/html/internals.asp

Articles 3. The ASP.NET Page Object Model
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dnaspp/html/aspnet-pageobjectmodel.asp


Zhu Ming

Take a look at this post on my blog, I hope it will give you the answer.

Fredrik's approach works, but it's a PITA (IMO) if it's to be done on every page (or in a common base class). We just discussed this the other day, so it's an alternative for you:

http://forums.asp.net/920819/ShowPost.aspx

-Brock

 

Thanks, Fredrik and Brock!

I've tried and both methods work!  As I need to toggle the culture for the whole web site instead of individual page, I prefer to do it in application's PreRequestHandlerExeute event handler.

Please refer to the help of HttpApplication Class.
An application executes events that are handled by modules or user code that is defined in the Global.asax file in the following sequence:
   1. BeginRequest
   2. AuthenticateRequest
   3. PostAuthenticateRequest
   4. AuthorizeRequest
   5. PostAuthorizeRequest
   6. ResolveRequestCache
      An event handler (a page corresponding to the request URL) is created at this point.
   7. PostResolveRequestCache
   8. PostMapRequestHandler
   9. AcquireRequestState
  10. PostAcquireRequestState
  11. PreRequestHandlerExecute
      The event handler is executed.
  12. PostRequestHandlerExecute
  13. ...

I tried BeginRequest, but it does not work.  I guess the reason is that the Page.Request will be created later and will overwrite the thread culture set in BeginRequest.
Till 10. PostAcquireRequestState, the request is prepared, and only after that can we change the thread culture.  Doing that in 11. PreRequestHandlerExecute is exactly Brock's approach.
"The event handler is executed." between 11 and 12 is the whole page's processing including any event handlers in the webform's codebehind, I think. Fredrik's approach, setting the thread culture in InitializeCulture is exactly here.

I still have one more problem.  The toggle button's event handler will be executed after the thread culture is set (either in PreRequestHandlerExecute or in InitializeCulture).  The result is that after the page reaches the browser the target culture will be different from the thread culture.  While in any other events, since the target culture is not changed, the target culture will be the same as the thread culture.  This is a inconsistent behavour.  But it is not much a ASP.NET technical problem.

Thanks!
Zhu Ming

Yep and for that last problem I always take the hack approach of Response.Redirect(Request.Path) to make the browser come back in so they see the changes immediaetly.

-Brock

 

It works!  The only drawback is that the input such as content in a TextBox will be gone after the redisplay of the same page.  The user has to enter it again.

Thanks, Brock!
Zhu Ming

I have another question.  Is there a way to localize web.sitemap?

Thanks!
Zhu Ming

Take a look at this post on my blog.

Thanks, Fredrik!

I like the implicit expression because it will save more typing.

<siteMap enableLocalization="true" xmlns="http://schemas.microsoft.com/AspNet/SiteMap-File-1.0" >
    <siteMapNode url="~/Default.aspx" title="Home"  description="" resourceKey="Home">

In addition, the web.sitemap.resx and its localized resources need to be put in App_GlobalResources folder.  (I'm using Beta 2.)

Zhu Ming

Can you give me an example of your global.asax file ?

I have a page with 4 resources like this :
Register.aspx.resx
Register.aspx.en-CAresx
Register.aspx.fr-CAresx
Register.aspx.fr-FR.resx

When I put a break point in the Page_load event, the resource manager is load with the Register.aspx.resx.  But my currentCulture is en-CA and the uiCulture is en.  Anyone can help me ?

Do you write the keyword new ?  Because it give me a warning if I don't do that.

new void PreRequestHandlerExecute(Object sender, EventArgs e)

{

   // create culture preference cookies if they don't exist yet
   // otherwise set current thread to value of those cookies
   System.Web.HttpCookie cookie = Request.Cookies["QuickStartLocalize"];

   if (cookie != null)
   {
      try
      {
         string currentUICulture = cookie.Values["UICulture"];
         string currentCulture = cookie.Values["Culture"];

         if ( currentUICulture != null && currentUICulture.Length > 0)
        {
            System.Threading.Thread.CurrentThread.CurrentUICulture = new System.Globalization.CultureInfo(currentUICulture);
         }

         if ( currentCulture != null && currentCulture.Length > 0)
         {
            System.Threading.Thread.CurrentThread.CurrentCulture =new System.Globalization.CultureInfo(currentCulture);
         }
      }
      catch (System.Exception)
      {
      }
   }
}

First, your resx files need to be named like this (notice the dot before resx):

Register.aspx.en-CA.resx
Register.aspx.fr-CA.resx

I guess they are just typos.

My Global.asax is shown below.

<%@ Application Language="C#" %>
<%@ Import Namespace="System.Globalization" %>
<%@ Import Namespace="System.Threading" %>

<script RunAt="server">
    // other methods are ommitted for brevity.

    protected void Application_PreRequestHandlerExecute(object sender, EventArgs e)
    {
        try
        {
            string lang = (string)Session["Language"];
            //Page.Culture = lang;  // This does not work!  Must assign Thread.CurrentThread.CurrentUICulture!
            Thread.CurrentThread.CurrentUICulture =
                new CultureInfo(lang);
        }
        catch
        {
        }
    }
</script>

You do not need to write the prototype yourself.  You can let Visual Studio do that for you.  There are two dropdown list above the code pane.  In the left dropdown list, select "Application".  And then in the right dropdown list, select the event handler you want such as "PreRequestHandlerExecute".  The event handler stub will be created for you.  Then you can write your code inside.

Hope this is of some use to you.

I have tried this and it works for a listbox selection and a button, but when I try it using an image button it fails in the application_prerequesthandlerexecute saying that session state in not available in this context - any ideas why?

I can't get it to work when I want to set the prefered languange in global.asax. I've tried both memberships and session. Membership always i nothing, and when I try to use sessions i get the error "Session state is not available in this context"

What am i doing wrong here?

This is in my global.asax in Application_PreRequestHandlerExecute

If Session("culture") IsNot Nothing Then
Try
Dim ci As New Globalization.CultureInfo(Session("culture").ToString)
System.Threading.Thread.CurrentThread.CurrentUICulture = ci
System.Threading.Thread.CurrentThread.CurrentCulture = ci
Catch ex As Exception
System.Threading.Thread.CurrentThread.CurrentUICulture = New System.Globalization.CultureInfo("sv-se")
End Try

End If

 

 

At the PreRequestHandlerExecute the Session variables is not yet available for use. What you can do is to store the culture into a cookie or maybe if you already use the Profile feature, you can use it to store the language a user has selected. You can also instead of the PreRequestHandlerExecute try to use the Application_AcquireRequestState.

 

Take a look at the following posts:

 

http://fredrik.nsquared2.com/viewpost.aspx?PostID=153

 

http://fredrik.nsquared2.com/viewpost.aspx?PostID=309

Works great with the profile feature. Thank you very much!