title: ASP.NET MVC Class level custom data-annotation and ModelState keys
body: <p>I have custom class level validation attribute, inheriting from ValidationAttribute, on my model.</p>
  
  <p>How come it doesn't register a key in the ModelState when its IsValid is false? I can see the the error message in the ModelState.Values collection, but the ModelState.Keys collection only shows an empty string "". Can I provide a key for it - presumably this is because its not assigned to a property?</p>
  
  <p>I wanna be able to use ModelState.Remove in my controller to remove this error upon a certain condition, but I have no Key!</p>
  
  <p>Any ideas?</p>