using chained scopes for facetted querying

gistfile1.rb

class Program < ActiveRecord::Base

  belongs_to :associated_school

  scope :active, -> { where("active = ?", true) }
  scope :inactive, -> { where("active = ?", false)}
  scope :in_country, ->(country) { 
                         joins(associated_school: 
                                        {school: :address}
                              ).where(addresses: 
                                      { country_code: country } 
                                     ) 
                              } 
  scope :with_language, ->(lang) { where("language=?", lang) } 
end


class ProgramsController < ApplicationController


  def index
    @programs = params.empty? ? Program.active : find_scoped(params)
  end
 

  private

    def find_scoped(args)
      @_programs = Program.active
      available_scopes = %w{ in_country with_language }

      available_scopes.each do |scope|
        if args[scope] && !args[scope].empty? 
          @_programs = @_programs.send(scope, args[scope] )
        end
      end
      
      @_programs
    end

end