Initialize default values in Rails

gistfile1.rb

# From: http://stackoverflow.com/a/5127684/638425
# WARNING: See the caveats.

class Person
  has_one :address
  after_initialize :init

  def init
    self.number  ||= 0.0           #will set the default value only if it's nil
    self.address ||= build_address #let's you set a default association
  end
end