Rails model inheritance with unique sets of fields

Question

I have a model BillService with basic set of fields. Next I want to create two models BillItem and BillGroup, which are the heirs of this and have the additional fields (each has a unique set). I also want to be able to get through the base class all instances of heirs and to check the class of concrete instance.

I can't imagine how to implement this. I tried to google it but nothing succeeded. I read about STI. That's what I need?

@ArupRakshit, Following STI, I should create table with union of all fieldsets? — Alexander Likhachev, Aug 10 '15 at 11:41
Yes all fields. :) With STI, we have one table, with a added `type` _string_ inside the field. — Arup Rakshit, Aug 10 '15 at 11:54

Gearnode · Answer 1 · 2015-08-10T13:04:19.030

ActiveRecord has native support of STI architecture.

Create BillService model

class BillService < ActiveRecord::Base

end

Create an folder bill_service and create your sti model in this folder

class BillService < ActiveRecord::Base

end

Add type field in your table bill_services

add_column :bill_services, :type, :string

Migrate

rake db:migrate

Use your STI

rails c

BillService::BillItem.all

BillService::BillItem.new

it's equal at

BillService.where(type: 'BillService::BillItem')

ActiveRecord set automatically type field by YouModel::YourSubModel.

Rails model inheritance with unique sets of fields

1 Answers1