Add a default value to a column through a migration

Question

How do I add a default value to a column that already exists through a migration?

All the documentation I can find shows you how to do it if the column doesn\'t alr

Answer 1

This is what you can do:

class Profile < ActiveRecord::Base
  before_save :set_default_val

  def set_default_val
    self.send_updates = 'val' unless self.send_updates
  end
end

EDIT: ...but apparently this is a Rookie mistake!