Django: AttributeError using ratings app

问题

This is somewhat an extension of my previous question, but after solving that problem I am getting a different AttributeError. This one reads '_RatingsDescriptor' object has no attribute 'cumulative_score' when trying to do something like this in my view:

def index(request):
    thing_list = Thing.ratings.cumulative_score()
    return render(request, 'index.html', {'thing_list':thing_list})

My model:

from ratings.models import Ratings

class Thing(models.Model):
    user = models.ForeignKey(User)
    ...
    ratings = Ratings()

While using django-simple-ratings app. This link references where cumulative_score is defined in that module. How do I use cumulative score for multiple objects? Thank you for your ideas!

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EDIT: views.py:

def index(request):
    thing_list = Thing.objects.all()
    thing_list.ratings.cumulative_score()
    return render(request, 'index.html', {'thing_list':thing_list})

回答1:

Its an instance method, so you must first retrive Thing from the db.

t = Thing.objects.get(xxxx)
t.ratings.cumulative_score()

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来源：https://stackoverflow.com/questions/14227478/django-attributeerror-using-ratings-app