dream_symbol.js.coffee

attr = DS.attr
App.DreamSymbol = DS.Model.extend
  image:        attr 'string'
  name:         attr 'string'
  description:  attr 'string'

  user:         DS.belongsTo 'user'

  parents:      DS.hasMany('dream_symbol', { embedded: 'always' })
  children:      DS.hasMany('dream_symbol', { embedded: 'always' })
  siblings:      DS.hasMany('dream_symbol', { embedded: 'always' })

  serialize: ->
    @getProperties [ 'guid', 'image', 'name', 'description', 'parents', 'children', 'siblings' ]

dream_symbol_serializer.rb

class DreamSymbolSerializer < ActiveModel::Serializer
  attributes  :id,
              :name,
              :description,
              :user_id,
              :image,
              :parents,
              :children,
              :siblings

  def parents
    object.ancestor_ids if !object.is_root?
  end

  def children
    object.descendant_ids if object.has_children?
  end

  def siblings
    object.sibling_ids if object.has_siblings?
  end
end

dream_symbols_controller.rb

  def show
    @dream_symbol = DreamSymbol.find( params[:id] )
    respond_with @dream_symbol, meta: { children: @dream_symbol.children, parents: @dream_symbol.ancestors, siblings: @dream_symbol.siblings }, meta_key: nil
  end

gistfile1.txt

%h1
  = hb 'name'
  %small
    %btn.btn.btn-default.btn-xls{ _action: 'edit' }
      %i.fa.fa-pencil

%p= hb 'description'

= hb 'each sibling in siblings' do
  = hb 'sibling.name'
  Woot

json_response.json

{"dream_symbol":{"id":1,"name":"Red","description":"xxx in the colour spectrum.","user_id":null,"image":"","parents":[3],"children":null,"siblings":[9,1]},"meta":{"children":[],"parents":[{"id":3,"name":"Colour","ancestry":"","description":"Various spectrums of light create all colours.","user_id":null,"image":"","created_at":"2014-04-03T04:26:13.446Z","updated_at":"2014-04-03T16:23:40.865Z"}],"siblings":[{"id":9,"name":"Blue","ancestry":"3","description":"ttttt","user_id":null,"image":null,"created_at":"2014-04-03T14:27:28.743Z","updated_at":"2014-04-06T15:16:30.388Z"},{"id":1,"name":"Red","ancestry":"3","description":"xxx in the colour spectrum.","user_id":null,"image":"","created_at":"2014-03-03T02:26:32.672Z","updated_at":"2014-04-05T00:04:44.909Z"}]}}

Found this article:
http://www.kaspertidemann.com/representing-objects-in-ember-data/

That's supposed to allow for embedded objects but that errors out.

So does the normal DS.hasMany() object.
I get the same error in both.