title: HashWithIndifferentAccess when saving array of objects
body: <p>Ok so I have these 2 classes</p>
  
  <pre><code>class Interface &lt; ActiveRecord::Base
    belongs_to :hardware      
  end
  </code></pre>
  
  <p>and</p>
  
  <pre><code>class Hardware &lt; ActiveRecord::Base
    has_many :interfaces
  end
  </code></pre>
  
  <p>I have a form for a predefined <em>@hardware.interfaces</em> which includes array of Interfaces which is handled like below</p>
  
  <pre><code>&lt;%= text_field_tag "hardware[interfaces][][name]",interface.name %&gt;
  &lt;%= text_field_tag "hardware[interfaces][][ip]",interface.ip %&gt;
  </code></pre>
  
  <p>Now I try to do...</p>
  
  <pre><code>@hardware = Hardware.find(params[:id])
  @hardware.update_attributes(params[:hardware]) 
  </code></pre>
  
  <p>and it throws the error</p>
  
  <pre><code>Interface(#37298420) expected, got HashWithIndifferentAccess(#24204840)
  </code></pre>
  
  <p>Could someone clue me in on what's going on? and how to solve this problem?</p>