Uploading different filetypes for different model properties

Question

I have a model with ImagePath and PDFPath properties.

When they click save, that calls the POST action method in the controller. I need to check that they have only uploaded image files and pdf files. If they have uploaded something other than these filetypes I want to set a ModelState error with the following:

ModelState.AddModelError("ImagePath", "Only image files are accepted");
ModelState.SetModelValue("ImagePath", new ValueProviderResult(null, null, null));

The problem is I need to set the correct properties in the AddModelError. The problem being they could have put a *.doc file in the ImagePath or PDFPath so I don't know which one to report as the error field.

How do I also make sure that they do only upload ceratin filetypes? RegEx?

Thanks

EDIT: Here is my controller code.

[AcceptVerbs(HttpVerbs.Post)]
    [Authorize]
    public ActionResult Create([Bind(Prefix = "", Exclude = "ID")] News item)
    {
        string imageUrl = "";
        string pdfurl = "";

        try
        {
            News.CheckForErrors(item);
        }
        catch (RulesException ex)
        {
            ex.AddModelStateErrors(ModelState, null);
        }

        foreach (string inputTagName in Request.Files)
        {
            HttpPostedFileBase file = Request.Files[inputTagName];
            if (file.ContentLength > 0)
            {
                string filePath = Path.Combine(HttpContext.Server.MapPath("/uploads"), Path.GetFileName(file.FileName));
                if (Path.GetExtension(file.FileName).ToLower() != ".jpg" || Path.GetExtension(file.FileName).ToLower() != ".pdf")
                {
                    //HELP! - Which model has the property error ImagePath/PDFPath?
                    ModelState.AddModelError("ImagePath", "Only JPG image files are accepted");
                    ModelState.SetModelValue("ImagePath", new ValueProviderResult(null, null, null));
                    break;
                }

                imageUrl = "/uploads/" + file.FileName;
            }
        }

        if (!ModelState.IsValid)
        {

                return View(item);

        }

        try
        {
            item.Save(User.Identity.Name);

        }
        catch (Exception x)
        {

        }



        return RedirectToAction("Index");

    }

Answer 1

You need something like GetFileByExtension() method:

HttpPostedFileBase GetFileByExtension(HttpFileCollectionBase files, string[] extensions)
{
    Func<string, bool> extensionIsValid =
        fileExtension => extensions.Any(
            extension => String.Compare(extension, fileExtension, true) == 0
        );

    return files.Cast<string>().Select(x => files[x]).Single(
        file => extensionIsValid(System.IO.Path.GetExtension(file.FileName))
        );
}

or:

IList<HttpPostedFileBase> GetAllFilesByExtension(HttpFileCollectionBase files, string[] extensions)
{
    Func<string, bool> extensionIsValid =
        fileExtension => extensions.Any(
            extension => String.Compare(extension, fileExtension, true) == 0
        );

    return files.Cast<string>().Select(x => files[x]).Where(
        file => extensionIsValid(System.IO.Path.GetExtension(file.FileName))
        ).ToList();
}

example:

var imageFile = GetFileByExtension(Request.Files,
                                   new [] { ".jpg", ".gif", ".png", ".bmp" });

var pdfFile = GetFileByExtension(Request.Files, new [] { ".pdf" });

or:

var imageFiles = GetAllFilesByExtension(Request.Files,
                                   new [] { ".jpg", ".gif", ".png", ".bmp" });

var pdfFiles = GetAllFilesByExtension(Request.Files, new [] { ".pdf" });

UPDATED:

Maybe you should try uploading using separate forms/actions for different uploads (something like /upload/create?newsid=1?uploadtype=image for images and /upload/create?newsid=1?uploadtype=pdf for PDFs). Your Upload.Create action could look like this:

public class UploadController : Controller
{
    public ActionResult Create(int newsId, string uploadType)
    {
        if(uploadType == "image")
        {
            // uploading only images
            var imageFiles = GetAllFilesByExtension(Request.Files, new [] { ".jpg", ".gif", ".png", ".bmp" });
            ...
        }
    }
}

In this case you always know the type of files, which should be uploaded to the action