Question

I have a situation where an action is called on a CallbackController. I have no control over this as it is prescribed by a framework. In response to this action I need to create a new Authentication. My AuthenticationController has create and a destroy actions.

How should I proceed? It seems to me my options are:

1. Duplicate the code from AuthenticationCOntroller’s create action into my CallbackController (Obviously far from DRY)
2. Call the create method directly from the CallbackController (This kind of inter-controller-communication seems to be frowned on)
3. Break the code from the AuthenticationController’s create action out into a helper class which is shared between the two controllers

None of these seem like the correct answer. So can anyone suggest a better approach?

My callbacks controller:

class Users::OmniauthCallbacksController < Devise::OmniauthCallbacksController

  def facebook
    authorize
  end


  def twitter
    authorize
  end

  private

    def authorize
      omniauth_data = request.env["omniauth.auth"]
      #Check to see if we have an authentication for this provider already
      authentication = Authentication.find_by_provider_and_uid(omniauth_data['provider'], omniauth_data['uid'])
      #If an authentication already exists, sign its User in
      #Otherwise create a new authentication for the current user
      if authentication
        flash[:notice] = "Signed in successfully with " +  omniauth_data['provider']
        sign_in_and_redirect(:user, authentication.user)
      elsif current_user
        current_user.authentications.create(:provider => omniauth_data['provider'], :uid => omniauth_data['uid'])
        flash[:notice] = "Authentication successful"
        redirect_to user_profile_url
      else
        user = User.new
        user.apply_omniauth_data_as_authentication(omniauth_data)
        if user.save
          flash[:notice] = "Signed in successfully with " +  omniauth_data['provider']
          sign_in_and_redirect(:user, authentication.user)
        else
          #save the omniauth data in a session so we can add the authentication once registration is complete
          session[:omniauth] = omniauth_data.except('extra')
          redirect_to new_user_registration_url
        end
      end
    end

end

and my authentications controller:

class AuthenticationsController < ApplicationController

  #Controller for representing Authentications provided by

  def index
    current_user.authentications if current_user
  end

  def create

  end

  def destroy
    @authentication = Authentication.find(params[:id])
    provider = @authentication.provider
    @authentication.destroy
    flash[:notice] = "Destroyed authentication from "+provider
    redirect_to authentications_url
  end

end

Answer 1

If you control the code for both CallbackController and AuthenticationController (they’re not coming from the framework), you could pull the common code out into a common superclass. Or just put it in a module and include it.

Rather than cut-and-pasting the entire create and destroy methods into a new Module, I would be inclined to find smaller, coherent parts and put them in methods with meaningful names. It may be that the create and destroy methods on both CallbackController and AuthenticationController can be implemented in just 2 or 3 lines using those smaller methods.

If you pull coherent groups of lines out into smaller methods, you could consider adding those methods as an extension to ActionController::Base if it seems appropriate. (i.e. if they are general enough.) If the small methods are useful in other parts of the application, that’s a bonus.