json.id attachment.uuid
json.title attachment.title
json.description attachment.description
json.filesize number_to_human_size(attachment.filesize)
json.is_pdf attachment.is_pdf?
json.url attachment.is_pdf? ? download_url(attachment,disposition:"inline") : download_url(attachment)
json.created_on attachment.created_on.strftime("%Y-%m-%d %H:%M:%S")
json.content_type attachment.content_type
json.creator do 
  json.partial! "api/v1/users/simple_user", locals: {user: attachment.author}
end