Rails: How to render different format.

codes_controller.rb

class CodesController < ApplicationController
  def index
    @codes = Code.all
    
    respond_to do |format|
      format.html
      format.json do
        render json: @codes,
               only: [:id, :name, :description]
      end
    end
  end
end

routes.rb

Opcs::Application.routes.draw do
  get "codes/index(.:format)"
end