class ActiveStorage::Preview

def url(**options)

a stable URL that redirects to the URL returned by this method.
This method synchronously processes a variant of the preview image, so do not call it in views. Instead, generate

preview has not been processed yet.
Returns the URL of the preview's variant on the service. Raises ActiveStorage::Preview::UnprocessedError if the 
def url(**options)
  if processed?
    variant.url(**options)
  else
    raise UnprocessedError
  end
end