How to select objects not referenced by foreign keys in Django 1.8?

Question

Django

Hello.
There is a model:

import datetime

from django.db import models
from django.utils import timezone


class Question(models.Model):
    question_text = models.CharField(max_length=200)
    pub_date = models.DateTimeField('date published')

    def __unicode__(self):
        return self.question_text

    def was_published_recently(self):
        now = timezone.now()
        return now - datetime.timedelta(days=1) <= self.pub_date <= now
        
    was_published_recently.admin_order_field = 'pub_date'
    was_published_recently.boolean = True
    was_published_recently.short_description = 'Published recently?'

class Choice(models.Model):
    poll = models.ForeignKey(Question)
    choice_text = models.CharField(max_length=200)
    votes = models.IntegerField()

    def __unicode__(self):
        return self.choice_text

The model describes the question-answers, one question can be assigned from 0 to N answers.
There is views.py:

from django.shortcuts import get_object_or_404, render
from django.http import HttpResponseRedirect
from django.core.urlresolvers import reverse
from django.views import generic
from django.utils import timezone

from .models import Choice, Question


class IndexView(generic.ListView):
    template_name = 'polls/index.html'
    context_object_name = 'latest_question_list'

    def get_queryset(self):
        """
        Return the last five published questions (not including those set to be
        published in the future).
        """
        return Question.objects.filter(
            pub_date__lte=timezone.now()
        ).order_by('-pub_date')[:5]

The essence of the question: What parameters to specify in Question.objects.filter() to receive only those questions for which there are options for answers?

Answer 1

from django.db.models import Count
Question.objects.annotate(count=Count('choice')).filter(count__gt=0)