title: MVC Validation and business layer
body: <p>The DataAnnotations validation happens in the default model binder and most of the examples I've seen uses the <code>Model.IsValid</code> in the Controller to verify if a model is valid or not. Since my controller action calls a business layer method and I like to validate the entity there:</p>
  
  <ol>
  <li>Do I have to explicitly switch off
  the model binder validation?</li>
  <li>How do I validate the entity in the
  business layer. In other words, how
  do I trigger validation given an
  object?</li>
  <li>Also, I am using View Models. Do I
  add the validation attributes to the
  view model? If so, since View models
  are being tied to the UI, what about
  validation at the business layer??</li>
  </ol>