public async Task <IHttpActionResult> UploadDocument(int targetFolder)
    {
        var uploadFileService = new UploadFileService();
        UploadProcessingResult uploadResult = await uploadFileService.HandleRequest(Request);

        if (uploadResult.IsComplete)
        {
            // do other stuff here after file upload complete
            return(Ok());
        }

        return(Ok(HttpStatusCode.Continue));
    }