ASP.NET MVC Controller FileContent ActionResult called via AJAX

Here's a quick example I made up. This is the concept LukLed was talking about with calling SaveFile but don't return file contents via ajax and instead redirect to the download.

Here's the view code:

<script src="../../Scripts/jquery-1.3.2.min.js" type="text/javascript"></script>
<script type="text/javascript">
    $(function() {
        // hide form code here

        // upload to server
        $('#btnUpload').click(function() {
            $.ajax({
                type: 'POST',
                dataType: 'json',
                url: '<%= Url.Action("SaveFile", "Home") %>',
                success: function(fileId) {
                    window.location = '<%= Url.Action("DownloadFile", "Home") %>?fileId=' + fileId;
                },
                error: function() {
                    alert('An error occurred uploading data.');
                }
            });
        });
    });
</script>

<% using (Html.BeginForm()) { %>

    <div>Field 1: <%= Html.TextBox("field1") %></div>

    <div>Field 2: <%= Html.TextBox("field2") %></div>

    <div>Field 3: <%= Html.TextBox("field3") %></div>

    <button id="btnUpload" type="button">Upload</button>

<% } %>

Here's the controller code:

[HandleError]
public class HomeController : Controller
{
    public ActionResult Index()
    {
        return View();
    }

    public JsonResult SaveFile(string field1, string field2, string field3)
    {
        // save the data to the database or where ever
        int savedFileId = 1;

        // return the saved file id to the browser
        return Json(savedFileId);
    }

    public FileContentResult DownloadFile(int fileId)
    {
        // load file content from db or file system
        string fileContents = "field1,field2,field3";

        // convert to byte array
        // use a different encoding if needed
        var encoding = new System.Text.ASCIIEncoding();
        byte[] returnContent = encoding.GetBytes(fileContents);

        return File(returnContent, "application/CSV", "test.csv");
    }

    public ActionResult About()
    {
        return View();
    }
}