class Participation < ActiveRecord::Base; end class PersonalProfile < ActiveRecord::Base; end class CreateParticipationRecords < ActiveRecord::Migration[4.2] def up event_to_speaker_profiles = execute "SELECT * FROM events_speaker_profiles" event_to_speaker_profiles.each do |event_to_speaker_profile| profile = PersonalProfile.find_by(id: event_to_speaker_profile["speaker_profile_id"]) next unless profile Participation.create! event_id: event_to_speaker_profile["event_id"], participant_id: profile.user_id, approved: true end end def down Participation.destroy_all end end