title: Doctrine - Add default time stamp to entity like NOW()
body: <p>Following the Doctrine guidelines I understand how to set a default value for an Entity, but what if I wanted a date/time stamp?</p>
  
  <ul>
  <li><a href="http://docs.doctrine-project.org/projects/doctrine-orm/en/2.1/reference/faq.html">http://docs.doctrine-project.org/projects/doctrine-orm/en/2.1/reference/faq.html</a></li>
  </ul>
  
  <p>My problem is my database has a default of NOW() on a field but when I use Doctrine to insert a record the values are null or blank but the rest of the insert happened.</p>
  
  <p>Also since Doctrine says to declare the default as a const, this also creates a problem.</p>
  
  <p>Suggestions?</p>