title: Doctrine findOneBy method not working
body: <p>I am creating small application with just two entities, Order and Shipment.</p>
  
  <p>The Shipment entity is as follows: (methods removed to keep it short)</p>
  
  <pre><code>/**
   * @var integer $id
   *
   * @ORM\Column(name="id", type="integer")
   * @ORM\Id
   * @ORM\GeneratedValue(strategy="AUTO")
   */
  private $id;
  
  /**
   * @var string $username
   *
   * @ORM\Column(name="username", type="string", length=255)
   */
  private $username;
  
  /**
   * @var string $password
   *
   * @ORM\Column(name="password", type="string", length=255)
   */
  private $password;
  
  /**
   * @var integer $order_id
   *
   * @ORM\Column(name="order_id", type="integer")
   */
  private $order_id;
  
  /**
   * @var smallint $payment_type
   *
   * @ORM\Column(name="payment_type", type="smallint")
   */
  private $payment_type;
  </code></pre>
  
  <p>In my controller I am trying to query using the <code>order_id</code> but my <code>findOneByOrderId</code> method is not working.</p>
  
  <pre><code>$orderExists = $this-&gt;getDoctrine()
                  -&gt;getRepository('ShipBundle:Shipment')
                  -&gt;findOneByOrderId($orderId);
  
  var_dump($orderExists);     die();
  </code></pre>
  
  <p>The error I get is:</p>
  
  <pre><code>Entity 'ShipBundle\Entity\Shipment' has no field 'orderId'. You can therefore not call 'findOneByOrderId' on the entities' repository.
  </code></pre>
  
  <p>If I am not wrong, Doctrine <code>find</code> methods join the variables at underscores and capitalize them. What am I doing wrong?</p>