title: Unobtrusive validation of collection
body: <p>My model contains a collection:</p>
  
  <pre><code>public ICollection&lt;int&gt; ChildAges { get; set; }
  </code></pre>
  
  <p>This is a dynamic list of ages that can be added to, this is all controlled via JQuery.</p>
  
  <p>giving me</p>
  
  <pre><code>&lt;select name="ChildAges"&gt;...&lt;/select&gt;
  &lt;select name="ChildAges"&gt;...&lt;/select&gt;
  &lt;select name="ChildAges"&gt;...&lt;/select&gt;
  etc...
  </code></pre>
  
  <p>If I add the standard <code>Required</code> attribute the validation returns true if any one value in the collection is set.</p>
  
  <p>How can I validate that all <code>ChildAges</code> in the form are set?</p>