Rails 5 in applicationHelper an helper is visible, another not

Question

I'm learning rails. I'm build a simple test application, with a simple authentication scheme. I'm using a user.role field to group the users. In my Application Helper i have:

module ApplicationHelper
def current_user
  if session[:user_id]
    @current_user ||= User.find(session[:user_id])
  else
    @current_user = nil
  end
end

def user_identity
  current_user.role if current_user
end
end

Now, in my app, i can use current_user in all controllers as expected, but instead user_identity is not visible.

why?

Answer 1

The application_helper is used mainly to access methods in views - I don't believe it's available in a controller.

The reason your 'current_user' method appears to work is that I'm assuming you're using Devise - when you call 'current_user' it is using the Engine's method rather than your own.

To solve this, write out a new module:

module MyHelper
  def current_user
    if session[:user_id]
      @current_user ||= User.find(session[:user_id])
    else
      @current_user = nil
    end
  end

  def user_identity
    current_user.role if current_user
  end
end

And in the controller you're using:

class MyController < ApplicationController
  include MyHelper

  bla bla bla...
end

Any methods defined in MyHelper will now be available in MyController, as we've included the module in the controller

Answer 2

Helper modules are mixed into the view context (the implicit self in your views) - not controllers.

So you can call it from the controller with:

class ThingsController < ApplicationController
  # ...
  def index
    view_context.user_identity
  end
end

Or you can include the helper with the helper method:

class ThingsController < ApplicationController
  helper :my_helper
  def index
    user_identity
  end
end

But if you're writing a set of authentication methods I wouldn't use a helper in the first place. Helpers are supposed to be aids for the view.

Instead I would create a concern (also a module) and include it in ApplicationController:

# app/controllers/concerns/authenticable.rb
module Authenticable
  extend ActiveSupport::Concern
  def current_user
    @current_user ||= session[:user_id] ? User.find(session[:user_id]) : nil
  end 

  def user_identity
    current_user.try(:role)
  end
end

class ApplicationController < ActionController::Base
  include Authenticable
end

Since the view can access any of the controllers methods this adds the methods to both contexts.