expires_at migration

class AddExpiresAtToOffer < ActiveRecord::Migration
  def change
    add_column :offers, :expires_at, :date
    Offer.reset_column_information
    
    puts 'Setting expiration dates...'
    
    Offer.find_each do |offer|
      expiration_date = offer.created_at + 6.months
      offer.update_column(:expires_at, expiration_date)
      print '.'
    end
    
    puts 'Done.'
  end
end