Question

I have many controllers where I want to set up a variable @top_tier_link that has the link to the index action of those controllers. Right now I have it like this:

class School::CoursesController < ApplicationController  
  before_filter :set_top_tier_link

  private
    def set_top_tier_link
      @top_tier_link = school_courses_path
    end
end

class School::UsersController < ApplicationController  
  before_filter :set_top_tier_link

  private
    def set_top_tier_link
      @top_tier_link = school_users_path
    end
end

I would like to define one before filter that can set that up automatically for any controller. How could I achieve that?

Edit:

This is just a sample, the number of controllers needing this kind of helper is much bigger. This variable is used at the layout level, so most controllers need this.

Answer 1

Define it in the ApplicationController. There you can differenciate based on the params[:controller] variable. Something like this:

before_filter :set_top_tier_link

def set_top_tier_link
  case params[:controller]
    when 'Courses'; @top_tier_link = school_courses_path
    when 'Users'; @top_tier_link = school_users_path
  end
end

Or even better to specify a helper for that, which does almost the same. Like this:

def top_tier_link
  @top_tier_link ||= case params[:controller]
    when 'Courses'; school_courses_path
    when 'Users'; school_users_path
  end
end

helper_method :top_tier_link

UPDATE: The path names can be generated automatically if you do not want to hardcode. A bit dangerous, but it should do the work:

def top_tier_link
  @top_tier_link ||= send(params[:controller].gsub("/","_")+"_path")
end