How to set Response Header before Server.Transfer in Asp.Net?

Question

I have a page where based on certain conditions I am either doing a Response.Redirect or Server.Transfer. Now I want to add a header for both the cases. So I am doing the fo

Answer 1

Andre is right that the Response object is replaced as part of Server.Transfer. If you want to make the page you're transferring to agnostic of the parent you can probably whack the information into HttpContext.Items and then use an IHttpModule to extract the information and configure the header appropriately. Something like this would probably do the job...

Items.Add(VaryHttpModule.Key, "User-Agent");

if (condition) 
{
    Server.Transfer(redirectUrl);
}
else
{
    Response.Redirect(redirectUrl);
}

public class VaryHttpModule : IHttpModule
{
    public const string Key = "Vary";

    public void Init(HttpApplication context)
    {
        context.PostRequestHandlerExecute +=
            (sender, args) =>
                {
                    HttpContext httpContext = ((HttpApplication)sender).Context;
                    IDictionary items = httpContext.Items;
                    if (!items.Contains(Key))
                    {
                        return;
                    }

                    object vary = items[Key];
                    if (vary == null)
                    {
                        return;
                    }

                    httpContext.Response.Headers.Add("Vary", vary.ToString());
                };
    }

    public void Dispose()
    {
    }
}

Cheers!