title: Unknown Attributes on nested form in Rails
body: <p>I'm having trouble getting my InventoryItem to accept nested attributes which is strange.</p>
  
  <p>In my script/console, I did the following:</p>
  
  <pre><code>&gt;&gt; InventoryItem.create!(:name =&gt; 'what', :image_attributes =&gt; [ {:image =&gt; File.open("/home/davidc/Desktop/letterbx.jpg", "r") }])
  ActiveRecord::UnknownAttributeError: unknown attribute: image_attributes
  </code></pre>
  
  <p>I am not sure why I'm getting the unknown attribute error when in my model, I already did accept_nested_attributes.</p>
  
  <p>I'm using Rails v2.3.5.</p>
  
  <p>Inventory Item Model</p>
  
  <pre><code>class InventoryItem &lt; ActiveRecord::Base
    uuid_it
  
    belongs_to :user
    has_many :orders
    has_many :images, :validate =&gt; true
    accepts_nested_attributes_for :images
  end
  </code></pre>
  
  <p>Image</p>
  
  <pre><code>class Image &lt; ActiveRecord::Base
    belongs_to :inventory_item
  
    has_attached_file :image, :style =&gt; { :medium =&gt; "300x300&gt;", :thumb =&gt; "100x100&gt;" }
  end
  </code></pre>