I have sucesfully configured custom file provider like this

  <slickUpload>

    <uploadProfiles>

      <add name="pc">

        <uploadStreamProvider type="PC.CustomFileUploadStreamProvider, PC" location="~/CustomFileNameFiles" />

      </add>

    </uploadProfiles>

  </slickUpload>

Overided class like this

 class CustomFileUploadStreamProvider : FileUploadStreamProvider

    {

        public CustomFileUploadStreamProvider(UploadStreamProviderElement settings)

            : base(settings)

        {

        }

        public override string GetServerFileName(UploadedFile file)

        {

            var processId = Guid.NewGuid().ToString();

            var path = Path.Combine(PC.Settings.GetFileStoragePath, processId);

            Directory.CreateDirectory(path);

            var serverFileName = Path.Combine(path, file.ClientName);

            file.Data.Add("ProcessId", processId);            

            return serverFileName;            

        }

    }

and I would like to pass custom data to my upload controller(I am using MVC).

Please note the line 

file.Data.Add("ProcessId", processId);

But when I try to read UploadSession class in upload controller there is no my custom data. How to pass data from FileUploadStreamProvider to UploadSession?

 public class HomeController : Controller

    {

        public ActionResult Index(UploadSession session)

        {

//MyCode

}

}