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.

Installation

Add this line to your application's Gemfile:

gem 'embedded_associations'

And then execute:

$ bundle

Or install it yourself as:

$ gem install embedded_associations

Usage

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).

Controller and Model Pre-Requisites

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

Strong Parameters

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]
)

Contributing

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