ActiveModel::Associations

has_many and belongs_to macro for Plain Ruby Object.

Installation

Add this line to your application's Gemfile:

gem 'activemodel-associations'

And then execute:

$ bundle

Or install it yourself as:

$ gem install activemodel-associations

Requirements

Ruby-2.0.0 or later

Support

activerecord-4.0.x
activerecord-4.1.x
activerecord-4.2.x
activerecord-5.0.x

Usage

belongs_to

class User < ActiveRecord::Base; end

class Comment
  include ActiveModel::Model         # need ActiveModel::Model
  include ActiveModel::Associations  # include this

  attr_accessor :body, :user_id # belongs_to association need foreign_key attribute

  belongs_to :user

  # need hash like accessor, used internal Rails
  def [](attr)
    self.send(attr)
  end

  # need hash like accessor, used internal Rails
  def []=(attr, value)
    self.send("#{attr}=", value)
  end
end

user = User.create(name: "joker1007")
comment = Comment.new(user_id: user.id)
comment.user # => <User {name: "joker1007"}>

Polymorphic belongs_to

class User < ActiveRecord::Base; end

class Comment
  include ActiveModel::Model         # need ActiveModel::Model
  include ActiveModel::Associations  # include this

  attr_accessor :body, :commenter_id, :commenter_type

  belongs_to :commenter, polymorphic: true

  # need hash like accessor, used internal Rails
  def [](attr)
    self.send(attr)
  end

  # need hash like accessor, used internal Rails
  def []=(attr, value)
    self.send("#{attr}=", value)
  end
end

user = User.create(name: "joker1007")
comment = Comment.new(commenter_id: user.id, commenter_type: "User")
comment.commenter # => <User {name: "joker1007"}>

has_many

class User < ActiveRecord::Base; end

class Group
  include ActiveModel::Model
  include ActiveModel::Associations

  attr_accessor :name
  attr_reader :user_ids

  has_many :users

  def [](attr)
    self.send(attr)
  end

  def []=(attr, value)
    self.send("#{attr}=", value)
  end
end

user = User.create(name: "joker1007")
group = Group.new(user_ids: [user.id])
group.users # => ActiveRecord::Relation (SELECT * from users WHERE id IN (#{user.id}))
group.users.find_by(name: "none") # => []

Limitation

Support associations is only belongs_to and simple has_many has_many options is limited. following options is unsupported.

:through :dependent :source :source_type :counter_cache :as

Contributing

Fork it ( https://github.com/joker1007/activemodel-associations/fork )
Create your feature branch (git checkout -b my-new-feature)
Commit your changes (git commit -am 'Add some feature')
Push to the branch (git push origin my-new-feature)
Create a new Pull Request

activemodel-associations

Development

Runtime