class MigrateProjetToStatisticProfile < ActiveRecord::Migration def up Project.all.each do |p| author = User.find(p.author_id) p.update_column( 'author_statistic_profile_id', author.statistic_profile.id ) end end def down Project.all.each do |p| statistic_profile = User.find(p.author_statistic_profile_id) p.update_column( 'author_id', statistic_profile.user_id ) end end end