title: How dont flush the persisted entity in Symfony2 with Doctrine?
body: <p>I have this action:</p>
  
  <pre><code>/**
   * @Route("/{id}", name="showpage", requirements={"id" : "\d+"})
   */
  public function showAction(Car $car, Request $request)
  {
      // I have fetched $car
      $form = $this-&gt;createForm(CarType::class, $car);
      $form-&gt;handleRequest($request);
      if ($form-&gt;isSubmitted() &amp;&amp; $form-&gt;isValid()) {
          $driver = new Driver();
          // Some logic...
          $em = $this-&gt;getDoctrine()-&gt;getManager();
          $em-&gt;persist($driver);
          $em-&gt;flush();
          //...
      }
      //..
   }
  </code></pre>
  
  <p>I want only get info and form by <code>$car</code>, but dont want update it.
  How can I block <code>flush()</code> for my <code>$car</code>?</p>