title: cannot use Url.Action in the class file
body: <p>in my asp.net mvc3 web site,  I use <code>Url.Action</code> in the view to generate url.</p>
  
  <pre><code>@Url.Action("Profile", "Users", new { @Id = Model.UserId, name = Model.NickName })
  </code></pre>
  
  <p>now, in one of my helper class, I need to do the same.  but get this error message, "The name 'Url' does not exist in the current context.</p>
  
  <p>is there another function I can use to generate url?</p>