EmbeddedModel

A simple extension for ActiveRecord allowing to embed plain-models and store them as JSON. It's well-suited in case the use of full-featured models with underlying tables is redundant.

Installation

Add this line to your application's Gemfile:

gem 'embedded_model'

And then execute:

$ bundle

Or install it yourself as:

$ gem install embedded_model

Current version of the gem works with ActiveRecord ~> 5 only, but previous one fits well for 4.2.

gem 'embedded_model', '~> 0.1.0'

Usage

Embeddable models

Any class allowing to populate their attributes by passing hash into constructor will suit.

class Person
  attr_accessor :name

  def initialize(attrs = {})
    @name = attrs.with_indifferent_access['name']
  end
end

I recommend using Virtus.

class Person
  include Virtus.model

  attribute :name, String
end

Embedding into container model

Add columns to be used as storage for embedded objects. If your database supports JSON (e.g. PostgreSQL), use type json, otherwise use text.

Use embeds_one method for embedding single objects and embeds_many for collections.

class Department < ActiveRecord::Base
  embeds_one :boss
  embeds_many :employees
end

By default, names of the embeddable models are inferred from the column names. Should your classes have other names, it is necessary to specify them explicitly.

class Party < ActiveRecord::Base
  embeds_one :tank, class_name: 'Player'
  embeds_many :dps, class_name: 'Player'
end

Example

As soon as everything gets done, it simply works.

department_params = {
  boss: { name: 'Todd' },
  employees: [{ name: 'Andy' }, { name: 'Jim' }]
}

department = Department.new(department_params)

# Do something with your model objects
department.boss.command('Work!')  # => Todd commands 'Work!'
department.employees.each(&:work) # => Andy works hard Jim works hard

department.save
department.reload

# Do something else
department.boss.command('Good job!') # => Todd commands 'Good job!'
department.employees.each(&:go_home) # => Andy goes home Jim goes home