title: undefined method error for :commenter in RailsGuides tutorial
body: <p>I'm working through the RailsGuides blog tutorial and am stuck:</p>
  
  <p>The error message I'm seeing reads:
  undefined method `commenter' for #</p>
  
  <p>The code looks like this:</p>
  
  <pre><code>&lt;h1&gt;&lt;%= @article.title %&gt;&lt;/h1&gt;
  &lt;br&gt;
  &lt;p&gt;&lt;%= @article.text %&gt;&lt;/p&gt;
  
  &lt;h2&gt;Comments&lt;/h2&gt;
  &lt;% @article.comments.each do |c| %&gt;
    &lt;p&gt;Commenter: &lt;%= c.commenter %&gt;&lt;/p&gt;
    &lt;p&gt;Comment: &lt;%= c.body %&gt;&lt;/p&gt;
  &lt;% end %&gt;
  
  &lt;h2&gt;Add a comment:&lt;/h2&gt;
  &lt;%= form_for([@article, @article.comments.build]) do |f| %&gt;
  
    &lt;p&gt;
      &lt;%= f.label :commenter %&gt;&lt;br&gt;
      &lt;%= f.text_field :commenter %&gt;
    &lt;/p&gt;
  
    &lt;p&gt;
      &lt;%= f.label :body %&gt;&lt;br&gt;
      &lt;%= f.text_area :body %&gt;
    &lt;/p&gt;
  
    &lt;p&gt;
      &lt;%= f.submit %&gt;
    &lt;/p&gt;
  
  &lt;% end %&gt;
  </code></pre>
  
  <p>The weird thing to me is that if I delete the ":commenter" section, the form works just fine.</p>