title: DataAnnotations validation and custom model binder
body: <p>I have an action method that accepts the following model - LanguagesViewModel:</p>
  
  <pre><code>public class LanguagesViewModel : ViewModelBase
  {
   IEnumerable&lt;LanguageItem&gt; Languages { get; set; }
  }
  
  public class LanguageItem
  {
   [Required]
   public int LanguageId { get; set; }
  
   [Required]
   public int SpeakingSkillId { get; set; }
  
   [Required]
   public int WritingSkillId { get; set; }
  
   [Required]
   public int UnderstandingSkillId { get; set; } 
  }
  </code></pre>
  
  <p>I also have a custom model binder to bind the POST data to the <code>IEnumerable&lt;LanguageItem&gt;</code>. </p>
  
  <p>The question is how do I get DataAnnotations validation to work?</p>