title: Initial data as queryset for formset foreign key field
body: <p>I am working on English language test application. There are questions and 4 possible answers for each question. Only one answer is correct.
  Here are the models:</p>
  
  <pre><code>class EnglishTestQuestion(AbstractDatetimeModel):
      text = models.CharField(max_length=255, verbose_name=u"Question text")
  
  class EnglishTestAnswerVariants(models.Model):
      question = models.ForeignKey(EnglishTestQuestion, verbose_name=_(u"question"), related_name='Variants')
      text = models.CharField(max_length=255, verbose_name=u"Text")
      is_correct = models.BooleanField(_(u"Is correct"), default=False)
  
  class EnglishTestAnswer(AbstractDatetimeModel):
      user = models.ForeignKey(User, blank=True, null=True, verbose_name=u"user")
      question = models.ForeignKey(EnglishTestQuestion, blank=False, verbose_name=u"question")
      answer = models.ForeignKey(EnglishTestAnswerVariants, verbose_name=u"answer")
  </code></pre>
  
  <p>Here is the view. I create a form for each question and pass initial data. Question field gets initial data, <strong>but Answer field ignores it and displays all answers</strong>,:</p>
  
  <pre><code>def english_test(request):
      questions = EnglishTestQuestion.objects.all()
      QuestionFormSet = formset_factory(form=EnglishTestForm, max_num=questions.count())
      formset = QuestionFormSet(initial=[{
                                             'question': x,
                                             'answer': EnglishTestAnswerVariants.objects.filter(question=x)
                                         } for x in questions])
  
      return render(request, 'testing/english_test.html', {"questions": questions, "question_formset": formset})
  </code></pre>
  
  <p><strong>But it should display for each question only those answers which connected via Foreign Key.</strong></p>
  
  <p>Here is form:</p>
  
  <pre><code>class EnglishTestForm(forms.ModelForm):
  
      class Meta:
          model = EnglishTestAnswer
          fields = '__all__'
          widgets = {
              'answer': forms.RadioSelect()
          }
  </code></pre>
  
  <p>How to pass in Answer field only those answers, which are connected with question by FK?</p>