Download file from controller RedirectToAction()

Question

I have an old MVC 1.0 application that I am struggling with something relatively simple.

1. I have a view that allows the user to upload a file.
2. Some server side processing goes on.
3. Finally, a new file is generated and downloads automatically to the client's machine.

I have steps 1 and 2 working. I can not get the final step to work. Here is my controller:

[AcceptVerbs(HttpVerbs.Post)]
public ViewResult SomeImporter(HttpPostedFileBase attachment, FormCollection formCollection, string submitButton, string fileName
{
    if (submitButton.Equals("Import"))
    {
        byte[] fileBytes = ImportData(fileName, new CompanyExcelColumnData());
        if (fileBytes != null)
        {
            RedirectToAction("DownloadFile", "ControllerName", new { fileBytes = fileBytes});
        }
        return View();
    }
    throw new ArgumentException("Value not valid", "submitButton");
}

public FileContentResult DownloadFile(byte[] fileBytes)
{
    return File(
                fileBytes,
                "application/ms-excel",
                string.Format("Filexyz {0}", DateTime.Now.ToString("yyyyMMdd HHmm")));
}

The code executes:

RedirectToAction("DownloadFile", "ControllerName", new { fileBytes = fileBytes});

but the file does not download. Suggestions welcome and thanks in advance.

Answer 1

Try to return ActionResult, because it is the most abstract class of the output of actions. ViewResult will force you to return a View or PartialView, so, return a File will get an exception about implicitly converttion type.

[HttpPost]
public ActionResult SomeImporter(HttpPostedFileBase attachment, FormCollection formCollection, string submitButton, string fileName
{
    if (submitButton.Equals("Import"))
    {
        byte[] fileBytes = ImportData(fileName, new CompanyExcelColumnData());
        if (fileBytes != null)
        {
            return File(
                fileBytes,
                "application/ms-excel",
                string.Format("Filexyz {0}", DateTime.Now.ToString("yyyyMMdd HHmm")));
        }
        return View();
    }
    throw new ArgumentException("Value not valid", "submitButton");
}

Answer 2

Why do RedirectToAction? Can you return File from SomeImporter action, just change the return type of SomeImporter to FileContentResult.