rails controller formatted error responses for multiple error types

rails_controller_formatted_responses.rb

module Api
  class ApiApplicationController < ActionController::Base
    protect_from_forgery
    before_filter :authenticate_api_user!

    rescue_from Exception,                            :with => :render_500
    rescue_from ActiveRecord::RecordNotFound,         :with => :render_404
    rescue_from ActionController::RoutingError,       :with => :render_404
    rescue_from ActionController::UnknownController,  :with => :render_404
    rescue_from ActionController::UnknownAction,      :with => :render_404

    private

    def render_404(exception)
      logger.error(exception)
      respond_to do |format|
        format.html { render :template => "/errors/404.html.erb", :status => 404 }
        format.any  do
          method = "to_#{request_format}"
          text = {}.respond_to?(method) ? {:error => 'not found'}.send(method) : ""
          render :text => text, :status => 404
        end
      end
    end

    def render_500(exception)
      logger.error(exception)
      respond_to do |format|
        format.html { render :template => "/errors/500.html.erb", :status => 500 }
        format.any  do
          method = "to_#{request_format}"
          text = {}.respond_to?(method) ? {:error => 'server error'}.send(method) : ""
          render :text => text, :status => 500
        end
      end
    end
  end
end