fab-manager/db/migrate/20190604070903_migrate_projet_to_statistic_profile.rb

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