title: Revalidating a modified ViewModel within a controller method?
body: <p><strong>EDIT</strong> - We're using MVC4 Dev Preview....</p>
  
  <p>I'm implementing an edit page for a <code>FishingTrip</code> class.  <code>FishingTrip</code> contains a child collection of simple <code>Crew</code> objects (i.e. FishingTripID, CrewID, CrewPosition).  </p>
  
  <p>I'm using <a href="http://jarrettmeyer.com/post/2995732471/nested-collection-models-in-asp-net-mvc-3" rel="noreferrer">Jarrett Meyer's approach</a> to add, edit and delete from the <code>Crew</code> collection.
  I'm using unobtrusive validation to specify that the properties of <code>Crew</code> are all <code>Required</code>.</p>
  
  <p>My problem: when I logically-delete an item from the list (as per Jarrett's method), I don't want that item to be validated.</p>
  
  <p>I have successfully tweaked the "removeRow" method on the client-side to disable unobtrusive validation for the logically-deleted item, so that the form will post despite there being an item that contains blank fields.  </p>
  
  <p>In my controller method <code>[HttpPost] Edit</code>, <code>ModelState.IsValid</code> starts off as false (as expected - because of the logically-deleted item that contains blank fields.)   So I remove that item from my ViewModel.... but <code>ModelState.IsValid</code> is still false.  </p>
  
  <p>In summary, I (think I) want to modify my ViewModel within the controller method to remove the offending item, then call some kind of "revalidate", and have <code>ModelState.IsValid</code> show up as true.</p>
  
  <p>Any ideas?</p>