class UpdateActivitiesData < ActiveRecord::Migration
  def up 	
  	count = Activity.all.count / 20 + 1
    transaction do
      for i in 1 ... count do i
        Activity.page(i).per(20).each do |activity|
          type = activity.act_type
          if type=='Contest' || type=='Message' || type=='News'|| type=='Journal'|| type=='Issue'|| type=='Principal'||type=='JournalsForMessage'
            activity.created_at = activity.act.created_on if activity.act
          elsif type=='Contestnotification' || type=='HomeworkCommon' || type=='Poll'
            activity.created_at = activity.act.created_at if activity.act
          end
          activity.save
	  	  end
      end
    end
  end

  def down
  end
end