i can't believe it's this hard to set default values at the AR object level (not the db level)

This is what I had to do:

  
  before_save :maybe_set_source

  def maybe_set_source
    self[:source] = source_name if !self[:source]
  end

  def source
    self[:source] || source_name
  end

  # The default value I want to set
  def source_name
    File.basename(RAILS_ROOT)
  end

Really?