title: django-formset package use in class base view
body: <p>when I use this package (<a href="https://pypi.org/project/django-formset/" rel="nofollow noreferrer">django-formset 0.8.8</a>) from &quot;FormCollections&quot; class after submit form redirect to success URL but the data doesn't saved in database</p>
  <p>this model is for quiz data for every device</p>
  <p><strong>model.py</strong></p>
  <pre><code>from django.db import models
  from device.models import Device
  
  
  class QuestionTraining(models.Model):
      ANSWER_CHOICES = (
          ('1', 'گزینه 1'),
          ('2', 'گزینه 2'),
          ('3', 'گزینه 3'),
          ('4', 'گزینه 4'),
      )
      device = models.ForeignKey(
          Device, on_delete=models.CASCADE, verbose_name='دستگاه')
      question = models.CharField(max_length=500, null=True)
      op1 = models.CharField(max_length=200, null=True)
      op2 = models.CharField(max_length=200, null=True)
      op3 = models.CharField(max_length=200, null=True)
      op4 = models.CharField(max_length=200, null=True)
      answer = models.CharField(max_length=1, choices=ANSWER_CHOICES, null=True)
  
      def __str__(self):
          return self.question
  </code></pre>
  <p>I use this form to show inline formset for each quiz</p>
  <p><strong>forms.py</strong></p>
  <pre><code>from django import forms
  from .models import QuestionTraining
  
  
  
  class CreateQuestionTrainingDeviceForm(forms.ModelForm):
      class Meta:
          model = QuestionTraining
  
          fields = ['device']
  
  
  class CreateQuestionTrainingForm(forms.ModelForm):
  
      class Meta:
          model = QuestionTraining
  
          fields = ['question', 'op1', 'op2', 'op3', 'op4', 'answer']
  
  class PhoneNumberForm(forms.Form):
      phone_number = forms.fields.CharField()
      label = forms.fields.CharField()
  
  
  class QuestionCollection(FormCollection):
      min_siblings = 1
      max_siblings = 5
      extra_siblings = 1
  
      question = CreateQuestionTrainingForm()
  
  
  class ContactCollection(FormCollection):
  
      divice = CreateQuestionTrainingDeviceForm()
      question = QuestionCollection()
  </code></pre>
  <p>after submitting form, the data doesn't save in database, but redirect to success URL</p>
  <p><strong>views.py</strong></p>
  <pre><code>class QuestionTrainingCreateView(FormCollectionView):
  
      template_name = 'question_training/create.html'
      collection_class = ContactCollection
      success_url = '/question_training/list'
  </code></pre>