title: Rails: update_attributes not updating all attributes
body: <p>I have a simple model called Discussion which has a boolean column called resolved.  </p>
  
  <p>In my form, I have the following code</p>
  
  <pre><code>&lt;%= form_for(@discussion) do |d| %&gt;
  ...
  &lt;%= d.check_box :resolved %&gt;
  &lt;% end %&gt;
  </code></pre>
  
  <p>And in my controller, I have the following:</p>
  
  <pre><code>def update
    @discussion = Discussion.find(params[:id])
    if @discussion.update_attributes(params[:discussion])
      etc...
    end
  end
  </code></pre>
  
  <p>When I submit the form, I can see that the parameters are being sent to the server...</p>
  
  <pre><code>Parameters: {"utf8"=&gt;"✓", "authenticity_token"=&gt;"AsGsRHwiVva/+kTrBs0IjLeZwj1ZmXBuKZr9Pg/N6Xk=", "discussion"=&gt;{"shortdesc"=&gt;"Talk about something.", "content"=&gt;"Try to update check box.", "resolved"=&gt;"1"}, "commit"=&gt;"Update Discussion", "id"=&gt;"1"}
  </code></pre>
  
  <p>But the query doesn't include anything about updating that field.</p>
  
  <pre><code>AREL (14.9ms)  UPDATE "discussions" SET "content" = 'Try to update check box.', "updated_at" = '2011-07-18 17:53:50.783176' WHERE "discussions"."id" = 1
  </code></pre>
  
  <p>Any idea on what I'm missing?</p>