title: JMSSerializerBundle RuntimeException: you must define a type for Entity::$field
body: <p>I'm having this issue with JMSSerializerBundle. It basically gives me an exception for something that I've already done. This is my entity:</p>
  <h3>Edited to avoid confusion about annotation lines</h3>
  <pre><code>&lt;?php
  
  namespace My\ProjectBundle\Entity;
  use JMS\SerializerBundle\Annotation\Type;
  
  use Doctrine\ORM\Mapping as ORM;
  
  /**
   * My\ProjectBundle\Entity\Music
   * 
   * @ORM\Table()
   * @ORM\Entity(repositoryClass=&quot;My\ProjectBundle\Entity\MusicRepository&quot;)
   */
  class Music extends Post
  {
  /**
   * @var integer $id
   * 
   * @ORM\Column(name=&quot;id&quot;, type=&quot;integer&quot;)
   * @ORM\Id
   * @ORM\GeneratedValue(strategy=&quot;AUTO&quot;)
   */
  protected $id;
  
  /**
   * @var string $album
   *
   * @ORM\Column(name=&quot;album&quot;, type=&quot;string&quot;)
   * @Type(&quot;string&quot;)
   */
  protected $album;
  
  /**
   * @var string $artist
   *
   * @ORM\Column(name=&quot;artist&quot;, type=&quot;string&quot;)
   * @Type(&quot;string&quot;)
   */
  protected $artist;
  
  /**
   * @var integer $duration
   *
   * @ORM\Column(name=&quot;duration&quot;, type=&quot;bigint&quot;)
   * @Type(&quot;int&quot;)
   */
  protected $duration;
  
  /**
   * @var string $title
   *
   * @ORM\Column(name=&quot;title&quot;, type=&quot;string&quot;)
   * @Type(&quot;string&quot;)
   */
  protected $title;
  
  /**
   * @var array $genres
   *
   * @ORM\Column(name=&quot;genres&quot;, type=&quot;array&quot;)
   * @Type(&quot;array&quot;)
   */
  protected $genres;
  </code></pre>
  <p>As you can see, I've added <code>@Type()</code> annotations for the fields, but it still gives me the exception when I call:</p>
  <pre><code>$listenedMusic = $serializer-&gt;deserialize($content, 'My\ProjectBundle\Entity\Music', 'json');
  </code></pre>
  <p>I've checked and the <code>$content</code> variable is not empty and has all the fields mapped in JSON format.</p>
  <p>In my Monolog files, this is the exact Exception:</p>
  <pre><code>[2012-11-29 23:39:07] request.CRITICAL: JMS\SerializerBundle\Exception\RuntimeException: 
  You must define a type for My\ProjectBundle\Entity\Music::$album. (uncaught exception) 
  at /vendor/jms/serializer-bundle/JMS/SerializerBundle/Serializer/GenericDeserializationVisitor.php line 177
  </code></pre>
  <p>Why does it still give me this exception?</p>