title: Required attribute for an integer value
body: <p>I have a viewmodel with an Id property</p>
  
  <pre><code>[Required]
  public int Id { get; set; }
  </code></pre>
  
  <p>But I think this attribute is working only for string properties.</p>
  
  <p>When no Id is set, Id has value 0 and the model is valid.</p>
  
  <p>How can I enforce that if no value for a int property is set, the model will be invalid ?</p>