title: Manually Set ModelState.isValid from Controller
body: <p>Is there a way for me to manually set the <code>ModelState.isValid = False</code> from the controller?</p>
  
  <p>I have some code like this</p>
  
  <pre><code>    Dim _region As Domain.Region = RegionService.GetRegionByNameAndParentID(user.UserRegion, user.ParentRegionID)
      If ModelState.IsValid AndAlso Not _region Is Nothing Then
             ''# ...
      Else
             Return View(user)
      End If
  </code></pre>
  
  <p>But if _region is nothing, then I don't get any Validation Errors firing.</p>
  
  <p>I thought about implementing a custom validator, but it would require hitting the database twice (once for validation and once to set the value).</p>