title: Combine DataAnnotations Validation with complex business rules
body: <p>I understand annotating class properties with the basic required and minimum length and getting all the benefits of the asp.net mvc server side and client side validation.</p>
  
  <p>However does anyone have a link that shows how you combine this 'base' validation with more complex business rules.  How would I run business rule functions, such as for example, has the customer ordered anything in the last year (database hit required) and still use the same DataAnnotation and mvc validation plumbing?</p>
  
  <p>Goal : Don't want two ways of generating and outputting validation methods.</p>