При сохранении формы я получаю эту ошибку: "" должно иметь значение для поля "surveythread» прежде чем можно будет использовать это отношение многие ко многим.

Models.py:

class SurveyResult(models.Model):
    stay = models.OneToOneField(Stay, related_name='survey')
    created = models.DateTimeField(default=datetime.now)
    vote = models.BooleanField(default=False)
    vote_service = models.BooleanField(default=False)
    comment = models.TextField(blank=True, null=True)

    def getThreads(self):
        return SurveyThread.objects.filter(parent_survey = self)

    threads = property(getThreads)

    def __unicode__(self):
        return self.vote and 'Good' or 'Bad'

    class Meta:
        get_latest_by = '-created'

class SurveyThread(models.Model):
    survey = models.ManyToManyField(SurveyResult, related_name='parent_survey')
    email = models.EmailField(max_length=200)
    comment = models.TextField(blank=True, null=True)

views.py:

survey_list = SurveyResult.objects.filter(stay__guest__user=request.user) \
                                      .select_related('stay', 'stay__guest')

forms = {}
for survey in survey_list:
  forms[survey] = SurveyThreadForm(data=request.POST or None, survey=survey)

  if forms[survey].is_valid():
    instance = forms[survey].save()
    return redirect('.')

forms.py

class SurveyThreadForm(forms.Form):

    comment = forms.CharField(required=False, widget=forms.Textarea)

    def __init__(self, *args, **kwargs):
        self.survey = kwargs.pop('survey', None)

        if not self.survey:
            raise NotImplementedError("SurveyResult object is required at this moment")

        super(SurveyThreadForm, self).__init__(*args, **kwargs)

        self.fields['comment'].label = "Message to send to guest:"

    def save(self, commit=True):
        s = SurveyThread()
        s.survey = self.survey
        s.email = "[email protected]"
        s.comment = self.cleaned_data['comment']

        if commit:
            s.save()
        return s

Сообщение об ошибке:

ValueError at /
"" needs to have a value for field "surveythread" before this many-to-many relationship can be used.
Request Method: POST
Request URL:    http://127.0.0.1:8000/
Django Version: 1.5.1
Exception Type: ValueError
Exception Value:    
"" needs to have a value for field "surveythread" before this many-to-many relationship can be used.
Exception Location: /Users/tlovett1/.virtualenvs/guestretain/lib/python2.7/site-packages/django/db/models/fields/related.py in __init__, line 586
Python Executable:  /Users/tlovett1/.virtualenvs/guestretain/bin/python
Python Version: 2.7.2
Python Path:    
['/Users/tlovett1/guestretain',
 '/Users/tlovett1/.virtualenvs/guestretain/lib/python2.7/site-packages/setuptools-0.6c11-py2.7.egg',
 '/Users/tlovett1/.virtualenvs/guestretain/lib/python2.7/site-packages/pip-1.3.1-py2.7.egg',
 '/Users/tlovett1/.virtualenvs/guestretain/lib/python27.zip',
 '/Users/tlovett1/.virtualenvs/guestretain/lib/python2.7',
 '/Users/tlovett1/.virtualenvs/guestretain/lib/python2.7/plat-darwin',
 '/Users/tlovett1/.virtualenvs/guestretain/lib/python2.7/plat-mac',
 '/Users/tlovett1/.virtualenvs/guestretain/lib/python2.7/plat-mac/lib-scriptpackages',
 '/Users/tlovett1/.virtualenvs/guestretain/Extras/lib/python',
 '/Users/tlovett1/.virtualenvs/guestretain/lib/python2.7/lib-tk',
 '/Users/tlovett1/.virtualenvs/guestretain/lib/python2.7/lib-old',
 '/Users/tlovett1/.virtualenvs/guestretain/lib/python2.7/lib-dynload',
 '/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7',
 '/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/plat-darwin',
 '/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-tk',
 '/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/plat-mac',
 '/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/plat-mac/lib-scriptpackages',
 '/Users/tlovett1/.virtualenvs/guestretain/lib/python2.7/site-packages',
 '/Users/tlovett1/.virtualenvs/guestretain/lib/python2.7/site-packages/PIL']
Server time:    Sun, 7 Jul 2013 10:22:55 -0500

Traceback: Я

Traceback Switch to copy-and-paste view

/Users/tlovett1/.virtualenvs/guestretain/lib/python2.7/site-packages/django/core/handlers/base.py in get_response
                        response = callback(request, *callback_args, **callback_kwargs) ...
▶ Local vars
/Users/tlovett1/guestretain/retain/apps/profiles/utils.py in _wrapped_view
                    return view_func(request, *args, **kwargs) ...
▶ Local vars
/Users/tlovett1/.virtualenvs/guestretain/lib/python2.7/site-packages/endless_pagination/decorators.py in decorated
            return view(request, *args, **kwargs) ...
▶ Local vars
/Users/tlovett1/guestretain/retain/apps/dashboard/views.py in dashboard
            instance = forms[survey].save() ...
▶ Local vars
/Users/tlovett1/guestretain/retain/apps/surveys/forms.py in save
        s.survey = self.survey ...
▶ Local vars
/Users/tlovett1/.virtualenvs/guestretain/lib/python2.7/site-packages/django/db/models/fields/related.py in __set__
        manager = self.__get__(instance) ...
▶ Local vars
/Users/tlovett1/.virtualenvs/guestretain/lib/python2.7/site-packages/django/db/models/fields/related.py in __get__
            through=self.field.rel.through, ...
▶ Local vars
/Users/tlovett1/.virtualenvs/guestretain/lib/python2.7/site-packages/django/db/models/fields/related.py in __init__
                                 (instance, source_field_name)) ...
▶ Local vars

Я новичок в Django и Python. Я могу опубликовать файл трассировки отладки или файла миграции, если это необходимо, но я чувствую этоПростое исправление. Очевидно, что я хочу сохранить несколько веток опроса для каждого результата опроса.

Спасибо!