public FileViewModel GetFile(ListItem file)
        {
            var path = Path.Combine(ConfigurationHelper.GetTemporaryFilesFolder(), file.Id, file.Value);
            if (File.Exists(path))
            {
                FileStream fsSource = null;
                try
                {
                    fsSource = new FileStream(path, FileMode.Open, FileAccess.Read);
                    var viewModel = new FileViewModel
                    {
                        FileName = file.Value,
                        InputStream = fsSource
                    };
                    return viewModel;
                }
                catch (Exception ex)
                {
                    if (fsSource != null)
                    {
                        fsSource.Dispose();
                    }

                    throw;
                }
            }

            return null;
        }
        public ListItem SaveAttachmentToTempFolder(FileViewModel fileViewModel)
        {
            var folderName = Guid.NewGuid().ToString();
            var path = Path.Combine(ConfigurationHelper.GetTemporaryFilesFolder(), folderName);
            Directory.CreateDirectory(path);
            using (var file = File.Create(Path.Combine(path, fileViewModel.FileName)))
            {
                fileViewModel.InputStream.CopyTo(file);
            }

            return new ListItem()
            {
                Value = fileViewModel.FileName,
                Id = folderName
            };
        }