title: Symfony 2 + Doctrine 2: find a record based on a date field using a DateTime value
body: <p>I have an entity called <code>Event</code>, with a field <code>startDate</code> (type="date"), and another called <code>slug</code> (type="string"). I have created a controller action to get a specific event based on these parts. The router passes eventDate as the format 'Y-m-d', and the eventSlug. Now I have successfully created a DateTime object with <code>$startDate = DateTime::createFromFormat('Y-m-d', $eventDate)</code>. Now if I issue</p>
  
  <pre><code>$event = $eventRepo-&gt;findOneBy(array(
      'startDate' =&gt; $startDate,
      'slug'      =&gt; $eventSlug,
  ));
  </code></pre>
  
  <p>it gets nothing (<code>$event</code> is NULL). Do I miss something in Doctrine documentation, or did I find a bug?</p>