title: post an array in rails
body: <p>This one is long to explain but basically my controller is built and expects an array in 
  <code>params[:order_items]</code>, so I've tried it like this:</p>
  
  <pre><code>&lt;%= hidden_field_tag "order_items", @order[:order_items_ids] %&gt;
  </code></pre>
  
  <p>but I get the ids concatenated </p>
  
  <pre><code>&lt;input id="gig_items" name="gig_items" type="hidden" value="2300124946"&gt;
  </code></pre>
  
  <p>So, How do I send and array in one of the <code>params</code> keys using just html (without js)? </p>