A simple way to deal with monetary amounts in cents, without using a library

amount_cents.rb

  #  amount_cents           :integer          default("0")

  def amount=(amount)
    amount = amount.gsub(/[^\d\.]/, '').to_f if amount.is_a?(String)
    self.amount_cents = amount * 100
  end

  def amount
    amount_cents / 100.0
  end

amount_cents should default to 0 or an exception may be raised.