core/db/migrate/20170509132020_change_enrollmentable_to_enrollable.rb
class ChangeEnrollmentableToEnrollable < ActiveRecord::Migration[5.0]
def change
rename_column :gaku_enrollments, :enrollmentable_id, :enrollable_id
rename_column :gaku_enrollments, :enrollmentable_type, :enrollable_type
end
end