Responding to a JSON PUT with either a 200 and the updated JSON or 204 and no body

resource_responder.rb

# The default Responder returns 200, {} for a PUT success.
# Not really happy with that. A 204, nil would be better.
# However, for most resources the result of a PUT is that something changes (updated_at).
# A 200 with the updated resource makes sense in that case.
#
# Not really happy with this first cut.
#
class ResourceResponder < ActionController::Responder
  protected

  def api_behavior(error)
    raise error unless resourceful?

    if get?
      display resource
    elsif has_errors?
      display resource.errors, :status => :unprocessable_entity
    elsif post?
      display resource, :status => :created, :location => api_location
    elsif put?
      # Simple PUTs end up with a has_changes? being true, not sure that is always the desired behavior
      if has_changes?
        display resource, :status =>  :ok, :location => api_location
      else
        display head(:no_content)
      end
      # Or for no response back, the correct status is
      # display head(:no_content)
    elsif has_empty_resource_definition?
      display empty_resource, :status => :ok
    else
      display head(:ok)
    end
  end

  def has_changes?
    resource.respond_to?(:previous_changes) && resource.previous_changes.any?
  end
end