Question

is it possible to both return a file for download and update a view from a controller method call?

or a workaround is needed, maybe using javascript (calling a refresh of the page after loading)?

the file download is created on the fly along the parameters set in a ViewModel
(search parameters from various controls on the page).

Answer 1

You can return the address of file using ViewModel or ViewData from your action, and use window.location.href as demonstrated in the following code at the end of your view.

Controller

public ActionResult Index()
{
    /* ... */

    ViewBag.FileName = "{FileName}";
    return View();
}

public ActionResult Download(string id) {
    /* ... */

    return File("{Path}", "{MIME type}", "{Desired file name}");
}

Markup

<script type="text/javascript">

    window.location.href = "/home/download/" + "@Ajax.JavaScriptStringEncode(@ViewBag.FileName)";

</script>