HABTM 3 deep nested
===

**ERROR :unknown attribute: size_id**

**Item Model**

    has_many :sizeables
    has_many :sizes, through: :sizeables, :dependent => :destroy

**Size Model**

    has_many :sizeables
    has_many :items, through: :sizeables
    
    has_one :centimeter
    accepts_nested_attributes_for :centimeter,  allow_destroy: true

**Centimeter Model**

    belongs_to :size

**Item Controller**

    def new 
        @item = Item.new
        @size = @item.sizes.build
        @size.build_centimeter  
    end

**Item New View**

    <%= f.fields_for :sizes do |s| %>
    <%= s.fields_for :centimeter do |c| %>
    <%= c.text_field :height %>
    <% end %>
    <% end %>

**ERROR :unknown attribute: size_id** 