demo_app/my_platform/db/migrate/20150325105846_make_profile_fields_polymorphic.your_platform.rb
# This migration comes from your_platform (originally 20120507165551)
class MakeProfileFieldsPolymorphic < ActiveRecord::Migration[4.2]
def change
change_table :profile_fields do |t|
# t.references :profileable, polymorphic: true
t.rename :user_id, :profileable_id
t.string :profileable_type
end
end
end