title: How to serialize groups of a user with Django-Rest-Framework
body: <p>I'm trying to get users groups with Django REST framework, but only what I got is empty field named "groups".</p>
  
  <p>This is my UserSerializer:</p>
  
  <pre><code>class UserSerializer(serializers.ModelSerializer):    
      class Meta:
          model = User
          fields = ('url', 'username', 'email', 'is_staff', 'groups')
  </code></pre>
  
  <p>any ideas how to get users groups data?</p>
  
  <p>thanks in advance</p>