Changing the name in the header for a resource handler in C#

Question

I have a resource handler that is Response.WriteFile(fileName) based on a parameter passed through the querystring. I am handling the mimetype correctly, but the issue is in some browsers, the filename comes up as Res.ashx (The name of the handler) instead of MyPdf.pdf (the file I am outputting). Can someone inform me how to change the name of the file when it is sent back to the server? Here is my code:

// Get the name of the application
string application = context.Request.QueryString["a"];
string resource = context.Request.QueryString["r"];

// Parse the file extension
string[] extensionArray = resource.Split(".".ToCharArray());

// Set the content type
if (extensionArray.Length > 0)
    context.Response.ContentType = MimeHandler.GetContentType(
        extensionArray[extensionArray.Length - 1].ToLower());

// clean the information
application = (string.IsNullOrEmpty(application)) ?
    "../App_Data/" : application.Replace("..", "");

// clean the resource
resource = (string.IsNullOrEmpty(resource)) ?
    "" : resource.Replace("..", "");

string url = "./App_Data/" + application + "/" + resource;


context.Response.WriteFile(url);

Answer 1

This Scott Hanselman post should be helpful:
http://www.hanselman.com/blog/CommentView.aspx?guid=360

Answer 2

Extending from Joel's comment, your actual code would look something like this:

context.Response.AddHeader("content-disposition", "attachment; filename=" + resource);

Answer 3

Thank you guys for your answer. The final code works and checks for pdf.

if (extensionArray[extensionArray.Length - 1].ToLower() == "pdf")
    context.Response.AddHeader("content-disposition", 
        "Attachment; filename=" + resource);