title: Additional Parameter in form_for in Rails
body: <p>Is it possible to submit another parameter outside the form data in rails? My problem is that I render different forms for different classes and send them to the same create method. I would like to send the class with the form (as value not as key in the hash).
  Something like the :type parameter (that actually doesn't work)</p>
  
  <pre><code>&lt;%= form_for(@an_object, :url =&gt; { :controller =&gt; :a_controller, :action =&gt; :create }, 
      :type =&gt; @an_object.class.to_s.underscore) do |f| %&gt;
  </code></pre>
  
  <p>The post message looks like:</p>
  
  <pre><code>{"commit"=&gt;"Create Class of an Object",
   "authenticity_token"=&gt;"/iqu0A8/AocDT3HyjL5/+bKZiLkyr4FE71u/mc8Wx0Y=",
   "utf8"=&gt;"âœ“",
   "class_of_an_object"=&gt;{"name"=&gt;"a name",
   "description"=&gt;"a description"}}
  </code></pre>
  
  <p>and I would have a <code>"type" =&gt; "class_of_an_object"</code>, but directly in the hash an not within the "class_of_an_object" hash.</p>