Presenters As A Solution To as_json Woes In Rails APIs

other_resource_presenter.rb

# app/presenters/api/v1/other_resource_presenter.rb
class Api::V1::OtherResourcePresenter

  attr_reader :other_resource

  def initialize( other_resource )
    @other_resource = other_resource
  end

  def as_json( include_root = false )
    data_hash = {
      :attr3 => @other_resource.attr3,
      :attr4 => @other_resource.attr4,
      :resource => resource
    }
    data_hash = { :other_resource => data_hash } if include_root
    data_hash
  end

  def resource
    Api::V1::ResourcePresenter.new( @other_resource.resource ).as_json( false )
  end

end

resource_controller.rb

# app/controllers/api/v1/resource_controller.rb
class Api::V1::ResourceController < Api::V1::BaseController

  def show
    @resource = Resource.find_by_id( params[:id] )
    render :status => 404 unless @resource
    @resource_presenter = Api::V1::ResourcePresenter.new( @resource ).as_json
    render :json => @resource_presenter
  end

end

resource_presenter.rb

# app/presenters/api/v1/resource_presenter.rb
class Api::V1::ResourcePresenter

  attr_reader :resource

  def initialize( resource )
    @resource = resource
  end

  def as_json( include_root = false )
    data_hash = {
      :attr1 => @resource.attr1,
      :attr2 => @resource.attr2
    }
    data_hash = { :resource => data_hash } if include_root
    data_hash
  end

end