Itemable

Make your ActiveRecord model as a item, it can be child or parent of self-modle or other-model

When will you need this gem?

Think about you are using PostgreSQL database, you just want to simplely store some unusually-query data into one table, put various files into one jsonb filed, record many have some child records, or parent records, such as a Car has many accessories: 4 Wheels, 3 Chairs, and a Wheel has one Tyre, 5 Screws. I don't care how to store them, just care about their relations, so now let's make this with Itemable:

1. Setup Itemable
2. Create Models Car, Wheel, Chair, Tyre, Screw
3. Create relations to each model

Installation

Add this line to your application's Gemfile:

gem 'itemable'

And then execute below to create tables itemable_items and itemable_item_relations:

$ rails g itemable:migration
$ rake db:migrate

Usage

Create Car modle

$ rails g model car name

Update app/models/car.rb:

class Car < ActiveRecord::Base
    acts_as_itemable
    has_many_items :wheels, dependent: :destroy
    has_many_items :chairs, dependent: :destroy
end

• acts_as_itemable makes Car has all feature of Itemable
• has_many_items :wheels declares a car has many wheels
• has_many_items :chairs declares a car has many chairs

Create Wheel model without db migration:

Add app/models/wheel.rb

class Wheel < ActiveRecord::Base
    acts_as_itemable sti: true
    belongs_to_item :car
    has_many_items :screws, dependent: :destroy
    has_one_item: :tyre, dependent: :destroy
end

• acts_as_itemable sti: true, sti = true means Wheel is a single table inherited Model, will get records from table itemable_items
• belongs_to_item :car declares wheel belongs to car
• has_one_item: :tyre declares wheel has only one tyre

Add app/models/chair.rb

class Chair < ActiveRecord::Base
    acts_as_itemable sti: true
    belongs_to_item :car
end

Add app/models/tyre.rb

class Tyre < ActiveRecord::Base
    acts_as_itemable sti: true
    belongs_to_item :wheel
end

Add app/models/screw.rb

class Screw < ActiveRecord::Base
    acts_as_itemable sti: true
    belongs_to_item :wheel
end

Now everything is ready, let store/query data

car = Car.create
4.times do
    car.wheels << Wheel.create
end
3.times do
    car.chairs << Chair.create
end
wheel = Wheel.first
wheel.tyre = Tyre.create
5.times do
    wheel.screws << Screw.create
end

car.reload
car.item_children.count => 7
car.item_children.map(&:child)
=> [#<Wheel:0x007f86ba65f930 id: 16, type: "Wheel", created_at: Fri, 07 Apr 2017 04:53:18 UTC +00:00, updated_at: Fri, 07 Apr 2017 04:53:18 UTC +00:00>,
 #<Wheel:0x007f86ba677fa8 id: 17, type: "Wheel", created_at: Fri, 07 Apr 2017 04:53:18 UTC +00:00, updated_at: Fri, 07 Apr 2017 04:53:18 UTC +00:00>,
 #<Wheel:0x007f86ba685568 id: 18, type: "Wheel", created_at: Fri, 07 Apr 2017 04:53:18 UTC +00:00, updated_at: Fri, 07 Apr 2017 04:53:18 UTC +00:00>,
 #<Wheel:0x007f86ba69c038 id: 19, type: "Wheel", created_at: Fri, 07 Apr 2017 04:53:18 UTC +00:00, updated_at: Fri, 07 Apr 2017 04:53:18 UTC +00:00>,
 #<Chair:0x007f86ba6cd0e8 id: 20, type: "Chair", created_at: Fri, 07 Apr 2017 04:53:22 UTC +00:00, updated_at: Fri, 07 Apr 2017 04:53:22 UTC +00:00>,
 #<Chair:0x007f86ba6e4e28 id: 21, type: "Chair", created_at: Fri, 07 Apr 2017 04:53:22 UTC +00:00, updated_at: Fri, 07 Apr 2017 04:53:22 UTC +00:00>,
 #<Chair:0x007f86ba706c58 id: 22, type: "Chair", created_at: Fri, 07 Apr 2017 04:53:22 UTC +00:00, updated_at: Fri, 07 Apr 2017 04:53:22 UTC +00:00>]
car.wheels.count => 4
=> [#<Wheel:0x007f86c018b8e0 id: 16, type: "Wheel", created_at: Fri, 07 Apr 2017 04:53:18 UTC +00:00, updated_at: Fri, 07 Apr 2017 04:53:18 UTC +00:00>,
 #<Wheel:0x007f86c018b750 id: 17, type: "Wheel", created_at: Fri, 07 Apr 2017 04:53:18 UTC +00:00, updated_at: Fri, 07 Apr 2017 04:53:18 UTC +00:00>,
 #<Wheel:0x007f86c018b5c0 id: 18, type: "Wheel", created_at: Fri, 07 Apr 2017 04:53:18 UTC +00:00, updated_at: Fri, 07 Apr 2017 04:53:18 UTC +00:00>,
 #<Wheel:0x007f86c018b430 id: 19, type: "Wheel", created_at: Fri, 07 Apr 2017 04:53:18 UTC +00:00, updated_at: Fri, 07 Apr 2017 04:53:18 UTC +00:00>]
car.chairs.count => 3
=> [#<Chair:0x007f86be2baab0 id: 20, type: "Chair", created_at: Fri, 07 Apr 2017 04:53:22 UTC +00:00, updated_at: Fri, 07 Apr 2017 04:53:22 UTC +00:00>,
 #<Chair:0x007f86be2ba830 id: 21, type: "Chair", created_at: Fri, 07 Apr 2017 04:53:22 UTC +00:00, updated_at: Fri, 07 Apr 2017 04:53:22 UTC +00:00>,
 #<Chair:0x007f86be2ba538 id: 22, type: "Chair", created_at: Fri, 07 Apr 2017 04:53:22 UTC +00:00, updated_at: Fri, 07 Apr 2017 04:53:22 UTC +00:00>]
wheels = car.wheels
wheels[0].item_children.count => 6
wheels[0].item_children.map(&:child)
=> [#<Tyre:0x007f86be44f290 id: 23, type: "Tyre", created_at: Fri, 07 Apr 2017 04:53:33 UTC +00:00, updated_at: Fri, 07 Apr 2017 04:53:33 UTC +00:00>,
 #<Screw:0x007f86be46e0f0 id: 24, type: "Screw", created_at: Fri, 07 Apr 2017 04:53:49 UTC +00:00, updated_at: Fri, 07 Apr 2017 04:53:49 UTC +00:00>,
 #<Screw:0x007f86be47cf60 id: 25, type: "Screw", created_at: Fri, 07 Apr 2017 04:53:49 UTC +00:00, updated_at: Fri, 07 Apr 2017 04:53:49 UTC +00:00>,
 #<Screw:0x007f86be497d38 id: 26, type: "Screw", created_at: Fri, 07 Apr 2017 04:53:49 UTC +00:00, updated_at: Fri, 07 Apr 2017 04:53:49 UTC +00:00>,
 #<Screw:0x007f86be4a6ba8 id: 27, type: "Screw", created_at: Fri, 07 Apr 2017 04:53:49 UTC +00:00, updated_at: Fri, 07 Apr 2017 04:53:49 UTC +00:00>,
 #<Screw:0x007f86be4b59f0 id: 28, type: "Screw", created_at: Fri, 07 Apr 2017 04:53:49 UTC +00:00, updated_at: Fri, 07 Apr 2017 04:53:49 UTC +00:00>]
wheels[0].tyre
=> #<Tyre:0x007f86b8fb04c8 id: 23, type: "Tyre", created_at: Fri, 07 Apr 2017 04:53:33 UTC +00:00, updated_at: Fri, 07 Apr 2017 04:53:33 UTC +00:00>
wheels[0].screws.count => 5
=> [#<Screw:0x007f86b833c750 id: 24, type: "Screw", created_at: Fri, 07 Apr 2017 04:53:49 UTC +00:00, updated_at: Fri, 07 Apr 2017 04:53:49 UTC +00:00>,
 #<Screw:0x007f86b833c570 id: 25, type: "Screw", created_at: Fri, 07 Apr 2017 04:53:49 UTC +00:00, updated_at: Fri, 07 Apr 2017 04:53:49 UTC +00:00>,
 #<Screw:0x007f86b833c3e0 id: 26, type: "Screw", created_at: Fri, 07 Apr 2017 04:53:49 UTC +00:00, updated_at: Fri, 07 Apr 2017 04:53:49 UTC +00:00>,
 #<Screw:0x007f86b833c250 id: 27, type: "Screw", created_at: Fri, 07 Apr 2017 04:53:49 UTC +00:00, updated_at: Fri, 07 Apr 2017 04:53:49 UTC +00:00>,
 #<Screw:0x007f86b833c0c0 id: 28, type: "Screw", created_at: Fri, 07 Apr 2017 04:53:49 UTC +00:00, updated_at: Fri, 07 Apr 2017 04:53:49 UTC +00:00>]
wheels[1].tyre => nil
wheels[1].tyre = Tyre.create
=> #<Tyre:0x007f86bbb8e450 id: 29, type: "Tyre", created_at: Fri, 07 Apr 2017 04:58:05 UTC +00:00, updated_at: Fri, 07 Apr 2017 04:58:05 UTC +00:00>
wheels[1].item_children.count => 1

See, it's so easy to build model relations

Advanced Usage

acts_as_itemable has following options:

• sti: true or false
• children: true or false
  • true generates association item_children, then support has_many_items
  • false does nothing
• child: true or false
  • true generates association item_child, then support has_one_item
  • false does nothing
• parents: true or false
  • true generates association item_parents, then support belongs_to_items
  • false does nothing
• parent: true or false
  • true generates association item_parents, then support belongs_to_item
  • false does nothing

options of has_many_items, has_one_item, belongs_to_items, belongs_to_item are the same to has_many or belongs_to

Test

rake

Contributing

Contribution directions go here.

License

The gem is available as open source under the terms of the MIT License.