title: Adding dynamic parameters with Html.BeginForm and jQuery submit
body: <pre><code>// html
  &lt;% using (Html.BeginForm("MyAction", "MyController", 
                     new { id = ViewContext.RouteData.Values["id"] },
                     FormMethod.Post, 
                     new { enctype = "multipart/form-data", class="myForm" }))
   { %&gt;
      &lt;input type="file" name="blah" /&gt;
   &lt;% } %&gt;
  
  
  
  // script
  $container.find('.myButton').click(function() {
      $container.find('.myForm').submit();
  });
  </code></pre>
  
  <p>Before the form is submitted, I need to add some extra parameters (route values) which can only be calculated at the time of submit.</p>
  
  <p>How do I do that?</p>