searchable.rb

module Searchable
  extend ActiveSupport::Concern

  included do
    scope :pg_search, ->(keyword){ where(search_query keyword) }
    include ClassMethods
  end

  module ClassMethods
    def search_against params
      @search_against ||= params if params.is_a? Array
    end

    def search_query keyword
      @search_against.map{|x| x.to_s + "~* '#{keyword}'"}.join(' or ') 
    end
  end
end


class Topic < ActiveRecord::Base
  include Searchable
  search_against [:title,:description,:body]
end