public IActionResult File(int id)
        {
            var file = announcementService.GetUploadedFile(id);

            if (file != null)
            {
                return new FileContentResult(file.Content, MimeTypeMap.GetMimeType(file.FileExtension))
                       {
                           FileDownloadName = file.FileName + file.FileExtension
                       }
            }
            ;
            else
            {
                return(NotFound());
            }
        }