title: Django: QuerySet object has no attribute
body: <p>I get an <code>AttributeError: 'QuerySet' object has no attribute 'ratings'</code> when trying to do something like this in my view:</p>
  
  <pre><code>def index(request):
      thing_list = Thing.ratings.cumulative_score()
      return render(request, 'index.html', {'thing_list':thing_list})
  </code></pre>
  
  <p>My model:</p>
  
  <pre><code>from ratings.models import Ratings
  
  class Thing(models.Model):
      user = models.ForeignKey(User)
      ...
      rating = Ratings()
  </code></pre>
  
  <p>While using <a href="https://github.com/coleifer/django-simple-ratings" rel="nofollow">django-simple-ratings</a> app. This <a href="https://github.com/coleifer/django-simple-ratings/blob/master/ratings/models.py#L206" rel="nofollow">link</a> references where <code>cumulative_score</code> is defined in that module. How do I use cumulative score?  Thank you for your ideas!</p>