EmbeddedAssociations

Provides ActionController-level support for embedded associations in Rails. Use cases include:

• Being able to easily consume embedded records serialized from Active Model Serializers.
• Simplifying REST API implementations.

Add this line to your application's Gemfile:

gem 'embedded_associations'

And then execute:

$ bundle

Or install it yourself as:

$ gem install embedded_associations

Embedded Associations provides an embedded_association macro to ActionController:

class PostsController < ApplicationController
  embedded_association :tags
  embedded_association :comments => :user
end

Inside of your controllers actions, the handle_embedded_associations method should be called:

def create
  params = params.require(:post).permit(:title, tags: [:name], comments: [:title, user: [:username]])
  post = Post.new
  handle_embedded_associations(post, params)
  post.update_attributes(params)
  render json: post
end

Behind the scenes, this will make the controller parse out sub-params passed in and perform the necessary ActiveRecord model manipulation. E.g., consider the params hash below:

{
  post: {
    tags: ['rest', 'ember-data'],
    comments: [
      {user: {name: 'Gordon'}}
    ]
  }
}

Based on the declared embedded_associations, the controller will manipulate the tags and comments association to reflect the passed in params (including deleting or creating child records).

When defining the relationships in the model, it is important to set the autosave and dependent options on the association:

class Post < ActiveRecord::Base
  has_many :comments, autosave: true, dependent: :destroy
  has_many :tags, autosave: true, dependent: :destroy
end

As might be expected, embedded associations must have their attributes permitted via the strong parameters api. For instance, a controller with the following embedded associates configuration:

embedded_association :comments => {:user => :account}
embedded_association :user => [:account]
embedded_association [:tags]
embedded_association :category

The attributes of the embedded associations must be explicitly permitted:

params.require(:post).permit(
  :title,
  comments: [:content, user: [:name, :email, account: [:note] ]],
  user: [:name, :email, account: [:note] ],
  tags: [:name],
  category: [:name]
)

1. Fork it
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create new Pull Request