title: Rails passing form_for object to partial
body: <p>I would like to pass the <code>form_for</code> object to a partial:</p>
  
  <pre><code>&lt;%= form_for @price do |f| %&gt;
     ...
     &lt;%= render :partial =&gt; "price_page", :object =&gt; @price, :as =&gt; :f %&gt;
     ...
  &lt;% end %&gt;
  </code></pre>
  
  <p>When I call:</p>
  
  <pre><code>f.radio_button
  </code></pre>
  
  <p>Brings the error:</p>
  
  <pre><code>undefined method `radio_button' for #&lt;Price:0x3cb1ed0&gt;
  </code></pre>
  
  <p>How can I use <code>f</code> as I usually would in this partial?</p>