title: get repository from Admin Class SonataAdminBundle
body: <p>I work with symfony 2.8 and SonataAdminBundle, I want to view the users who are 'client' and here is my code:</p>
  
  <p><strong>ClientAdmin</strong></p>
  
  <pre><code> protected function configureListFields(ListMapper $listMapper)
  {
  
       $result = $this-&gt;getConfigurationPool()-&gt;getContainer()-&gt;get('Doctrine')-&gt;getRepository('UserBundle:User')-&gt;findClient();
  
      $listMapper
  
          -&gt;add('client', 'sonata_type_model', array(
              'empty_value' =&gt; '', 
              'choice_list' =&gt; $result))
  
                ;
  }
  </code></pre>
  
  <p><strong>UserRepository</strong></p>
  
  <pre><code>public function findClient()
  {   $dql = "SELECT p FROM UserBundle:User p WHERE p.type LIKE 'client' ORDER BY p.id DESC";
      return $this-&gt;getEntityManager()
          -&gt;createQuery($dql)
  
          -&gt;getResult();
  }
  </code></pre>
  
  <p>But it does not work and still no result</p>