How add Helpers in API-only Rails Application

Question

I created a API-Only Rails Application but I need a administrative area to manage data. So I created this controller:

require 'rails/application_controller'
require_relative '../helpers/admin_helper'
class AdminController < Rails::ApplicationController
  include AdminHelper
  def index
    @q = Promotion.search(params[:q])
    @promotions = @q.result(distinct: true).page(params[:page]).per(30)
    render file: Rails.root.join('app', 'views', 'admin', 'index.html')
  end
end

Bot I can't access Helper, even requiring the module. Look a Helper:

module AdminHelper
  def teste
    'ok'
  end
end

And the error generated:

ActionController::RoutingError (uninitialized constant AdminController::AdminHelper):

Answer 1

So, I was able to make this work in a new application running rails new my_api_test_app --api and then including the below files. I don't think you need the require statements in the controller. You can just include the helper as you've done. I've included the file structure location that I used for each file (notably, I put the helper in app/helpers/admin_helper.rb , which may be what you need for file to load properly.

#app/controllers/admin_controller.rb
class AdminController < Rails::ApplicationController
  include AdminHelper
  def index
    test
    render file: Rails.root.join('app', 'views', 'admin', 'index.html')
  end
end


#app/helpers/admin_helper.rb
module AdminHelper
  def test
    puts "tests are really fun"
  end
end

#config/routes
Rails.application.routes.draw do
  root 'admin#index'
end

#index.html.erb
Hello World!

And in the rails log, I get this:

app/controllers/admin_controller.rb:5:in `index'
Started GET "/" for 127.0.0.1 at 2017-02-15 15:26:32 -0800
Processing by AdminController#index as HTML
tests are really fun
  Rendering admin/index.html.erb within layouts/application
  Rendered admin/index.html.erb within layouts/application (0.3ms)
Completed 200 OK in 8ms (Views: 8.0ms | ActiveRecord: 0.0ms)

Note that tests are really fun printed in the log.

Answer 2

If you are using ActionController::API (and you should when implementing APIs), you can make use of application helpers by including the dedicated mixin :

class Api::V1::ApiController < ActionController::API
  include ActionController::Helpers
  helper MyHelper
end

Answer 3

Full example:

at: app/controllers/admin_controller.rb

class AdminController < ActionController::API
  include ActionController::Helpers
  helper AdminHelper
  def index
    test = ApplicationController.helpers.test('test')
    render json: test
  end
end

at: app/helpers/admin_helper.rb

module AdminHelper
  def test(args)
    return args
  end
end

you can use rails generate rspec:helper to generate test

RSpec.describe AdminHelper, type: :helper do
  it "return args" do
    expect(helper.args('yo'))
        .to eq('yo')
  end
end

• As noted by @Ghis it is better to use ActionController::API.
• Documentation for ApplicationController.helpers https://api.rubyonrails.org/classes/ActionController/Helpers.html#method-i-helpers
• Why it is better to use ApplicationController.helpers than include the module? the modules instance methods would become controller methods https://ruby-doc.org/core-2.2.0/Module.html https://medium.com/little-programming-joys/using-helper-methods-inside-your-controllers-51dd5e39ee72