title: Rails: Ignore nested attributes with a certain name?
body: <p>Basing this functionality off of Ryan Bates <a href="http://railscasts.com/episodes/197-nested-model-form-part-2" rel="nofollow">Nested Model Form</a> tutorials, when I submit my form, I've got this set of data that's submitted:</p>
  
  <pre><code>{
      "authenticity_token"=&gt;"mdohADjieoqUwOwUK/H52TAiH5HdFYQtTbTuMJtDJE8=",
       "utf8"=&gt;"✓",
       "id"=&gt;"92",
       "survey"=&gt;
      {
          "questions_attributes"=&gt;
          {
              "1299616889104"=&gt;
              {
                  "display_type"=&gt;"",
                   "text"=&gt;"",
                   "other"=&gt;"0",
                   "display_order"=&gt;"0",
                   "answer_choices"=&gt;"",
                   "item_type"=&gt;"multiple_choice"
              },
               "new_questions"=&gt;
              {
                  "display_type"=&gt;"compare",
                   "pick"=&gt;"one",
                   "text"=&gt;"",
                   "other"=&gt;"0",
                   "display_order"=&gt;"0",
                   "answer_choices"=&gt;"",
                   "item_type"=&gt;"compare"
              }
          },
           "id"=&gt;"92"
      }
  }
  </code></pre>
  
  <p>What I need to figure out how to do is ignore the <code>new_questions</code> section. I know you can add <code>reject_if</code> to <code>accepts_nested_attributes_for</code> but there are hidden fields that are included and pre-populated with data, so I can't ignore based on empty fields.</p>
  
  <p>So how can ignore <code>new_questions</code> in my example data?</p>
  
  <p>I'm running Rails 3.0.3</p>