How to force download in MVC2?

I have a pdf and want to offer the user a simple "Download" link. How can this be made?

My idea is

- to compute the url to the pdf document on server side and store it in "viewmodel.PDFURL",

- add a <a href=...> to the view which calls a function.

- This function would use

$.post("ForcePDFDownload", { PDFURL: <%: Model.PDFURL %> } );

to call this serverside method:

[HttpPost]
public JsonResult ForcePDFDownload(string PDFURL)
{
    string path = Path.GetFullPath(PDFURL);
    string filename = Path.GetFileName(PDFURL);
    Response.AppendHeader("content-disposition", "attachment; filename=" + filename);
    Response.ContentType = "application/pdf";
    Response.WriteFile(path);
    R开发者_JAVA百科esponse.End();

    return null;
}

But return null; makes no sense to me, but the methode must return something, otherwise wont Visual Studio compile...

Any idea?

Thanks in Advance!

---

No need to use JSON, ajax, jquery or whatever. Simply:

public ActionResult ForcePDFDownload(string PDFURL)
{
    string path = Path.GetFullPath(PDFURL);
    string filename = Path.GetFileName(PDFURL);
    Response.AppendHeader("Content-Disposition", "attachment; filename=" + filename);
    return File(path, "application/pdf");
}

And then construct a link:

<%: Html.ActionLink("Download PDF", "ForcePDFDownload", new { PDFURL = Model.PDFURL }) %>

Be extremely careful when exposing such action on your server as a hacker could always type the following address in his favorite browser:

http://foo.com/somecontroller/forcepdfdownload/?pdfurl=c%3A%5Cmycreditcardnumbers.txt

and live happily to the rest of his life :-)