Sometimes you want to change the database and massage the data so that it will fit with the new schema. For this to work, the migration should do two things:

1. turn off timestamps by setting record_timestamps to false so that when you save records they will not show up as recently modified.
2. call reset_column_information so that the new columns that have been added in the same migration will show up in the ActiveRecord objects.

class SplitProfileNameIntoFirstAndLastNames < ActiveRecord::Migration

  def self.up
    add_column :profiles, :first_name, :string
    add_column :profiles, :last_name, :string

    ActiveRecord::Base.record_timestamps = false
    Profile.reset_column_information    
    Profile.find(:all).each do |profile|
      profile.first_name = profile.name.split(" ").first
      profile.last_name  = profile.name.split(" ").last
      profile.save!
    end

    remove_column :profiles, :name
  end

  def self.down
    add_column :profiles, :name, :string

    ActiveRecord::Base.record_timestamps = false
    Profile.reset_column_information
    Profile.find(:all).each do |profile|
      profile.name = profile.first_name + " " + profile.last_name
      profile.save!
    end

    remove_column :profiles, :first_name
    remove_column :profiles, :last_name
  end
end