def to_fileupload
      {
        id: id,
        name: filename,
        content_type: content_type,
        size: size,
        url: url,
        thumb_url: thumb_url
      }
    end
def to_fileupload
      {
        id: id,
        name: filename,
        content_type: content_type,
        size: size,
        url: url,
        thumb_url: thumb_url
      }
    end
Serialize asset to fileupload JSON format