title: String of certain length in Sailsjs Model
body: <p>How can I enforce a Model property to be exactly 32 characters long?</p>
  
  <p>I have tried </p>
  
  <pre><code>key : {
      type: 'string',
      len : 32
  }
  </code></pre>
  
  <p>but it doesn't work.</p>