has_sti

has_sti is an ActiveRecord extension that provides helper methods and scopes for STI models.

• Add has_sti to your Gemfile:

gem 'has_sti'

• Install with: bundle install

We will use Ruby on Rails for this scenario. Let's say User model is a parent STI class and you want to create child classes: Admin and Reader. You start with defining STI as follows:

class User < ActiveRecord::Base
end

class Admin < User
end

class Reader < User
end

Next step is creating migration for the database: rails generate migration AddTypeToUser type:string

Then, we need to migrate database: bundle exec rake db:migrate

Basic setup of STI is done. Here's where has_sti takes action.

Modify your User model to include has_sti:

class User < ActiveRecord::Base
  has_sti :admin, :reader
end

And that's it. Now you have following methods and scopes available:

some_admin = Admin.create

some_admin.admin? => true
some_admin.reader? => false

User.admin => [some_admin]
User.reader => []

You can also disable helper methods:

class User < ActiveRecord::Base
  has_sti :admin, :reader, helper_methods: false
end

or scopes:

class User < ActiveRecord::Base
  has_sti :admin, :reader, scopes: false
end

or even set it per child class:

class User < ActiveRecord::Base
  has_sti :admin, scopes: false
  has_sti :reader, helper_methods: false
end

No configuration is required. Custom STI column name is supported.

has_sti is released under the MIT license:

• http://www.opensource.org/licenses/MIT

Arkadiusz Fal

• http://arekf.net

Copyright © 2015