Sander Sander - 3 months ago 48
Ajax Question

Is there any workaround for the UpdatePanel + Server.Transfer problem?

I'm trying to use an UpdatePanel in my ASP.NET application. Unfortunately, it seems that I can't do this if I am using Server.Transfer() in my application.

Modifying that component of the application is not possible - the architecture makes extensive use of Server.Transfer() - in essence, every page request goes through this method. Does any workaround exist for this issue exist? Having to do full-page postbacks is so unfashionable these days...

Answer

I've got it! Thank Og for strange foreign language blogs :)

To fix it, I can simply tell the ASP.NET AJAX client-side framework to direct the partial request directly at the real target of the Server.Transfer() call. I am quite scared of the possible side-effects (who knows what this skips - the infrastructure does have a purpose) but it seems to be working fine so far.

Here is the method that fixes the problem, called in my page's Load event:

	///
	/// Adds to the page a JavaScript that corrects the misbehavior of AJAX when a page is target of a Server.Transfer call.
	///
	protected void AjaxUrlBugCorrection()
	{
		string actualFile = Server.MapPath(AppRelativeVirtualPath);
		string redirectFile = Server.MapPath(Context.Request.FilePath);
		string baseSiteVirtualPath = HttpRuntime.AppDomainAppVirtualPath;

		if (actualFile != redirectFile)
		{
			System.Text.StringBuilder sbJS = new System.Text.StringBuilder();
			string actionUrl = string.Format("'{0}'", baseSiteVirtualPath + AppRelativeVirtualPath.Replace("~", String.Empty));
			sbJS.Append("Sys.Application.add_load(function(){");
			sbJS.Append(" var form = Sys.WebForms.PageRequestManager.getInstance()._form;");
			sbJS.Append(" form._initialAction = " + actionUrl + ";");
			sbJS.Append(" form.action = " + actionUrl + ";");
			sbJS.Append("});");
			ClientScript.RegisterStartupScript(this.GetType(), "CorrecaoAjax", sbJS.ToString(), true);
		}
	}