before_filter

gistfile1.rb

class Admin::TopicsController < ApplicationController

  # this could be an example of a before filter
  before_filter :check_security_token

  def create

    topic = Topic.new(params[:topic])

    # move this to AR callback before_create ?
    topic.started_trending = Time.now
    topic.save

    render :nothing => true
  end
  
  def edit
  end
  
  def update
    # check_security_token
    # updates mentions
  end


  private

    def check_security_token
      unless params[:security_token].present? && params[:security_token] == BestPractices::SECURITY_TOKEN
        render :nothing => true
      end
    end

end

topic.rb

class Topic < ActiveRecord::Base
  
  before_create :set_start_trending

  scope :trending_top, lambda { |num| where("started_trending > ?", 1.day.ago).order('mentions desc').limit(num) }
  
  
  private

    def set_start_trending
      self.started_trending = Time.now
    end

end