http://d.hatena.ne.jp/foosin/20090428/1240914523 適当に試したらでけたのでメモ。 app/helpers/migration_helper.rb module MigrationHelper def foreign_key(from_table, from_column, to_table) constraint_name = "fk_#{from_table}_#{to_table}" execute "alter table #{from_table} add constraint #{constraint_name} foreign key (#{from_column}) references #{to_table}(id)" end end module ActiveRecord module ConnectionAdapters