title: How to Add a check Constraint to Doctrine Annotation in Symfony
body: <p>Suppose I have a field <code>gender</code> in my <code>Person</code> entity which can take any of following values</p>
  
  <ul>
  <li>MALE</li>
  <li>FEMALE</li>
  <li>OTHERS</li>
  </ul>
  
  <p>How can I provide this check using doctrine ORM annotation and then create a corresponding radio button in form using <code>php app/console generate:doctrine:crud</code>?</p>
  
  <p>Can I do that directly? Or do I have to rely on manual approach?</p>