CBV with Multiple forms. Based on UpdateView.

views.py

class MultipleFormsView(ItemUpdate):
    model = MyModel
    template_name = ''
    success_url = reverse_lazy('')

    form_class = Form1
    second_form_class = Form2
    third_form_class = Form3


    def get_context_data(self, **kwargs):
        context = super(MultipleFormsView, self).get_context_data(**kwargs)

        if 'form' not in context:
            context['form'] = self.form_class(
              initial={
                  'some_field_1': self.get_object().some_field_1,
                  'some_field_2': self.get_object().some_field_2, 
                })

        if 'form1' not in context:
            context['form1'] = self.second_form_class(
              initial={
                  'some_field_3': self.get_object().some_field_3,
                  'some_field_4': self.get_object().some_field_4, 
                })

        if 'form2' not in context:
            context['form2'] = self.third_form_class(
              initial={
                  'some_image': self.get_object().some_image 
              })

        return context


    def form_invalid(self, **kwargs):
        return self.render_to_response(self.get_context_data(**kwargs))


    def get_object(self, queryset=None):
        if queryset is None:
            queryset = self.get_queryset()

        pk = self.kwargs.get(self.pk_url_kwarg)
        slug = self.kwargs.get(self.slug_url_kwarg)

        if pk is not None:
            queryset = queryset.filter(pk=pk)

        if slug is not None and (pk is None or self.query_pk_and_slug):
            slug_field = self.get_slug_field()
            queryset = queryset.filter(**{slug_field: slug})

        if pk is None and slug is None:
            raise Http404
        try:
            obj = queryset.get()
        except queryset.model.DoesNotExist:
            raise Http404()

        return obj


    def post(self, request, *args, **kwargs):
        self.object = self.get_object()

        if 'form' in request.POST:
            form_class = self.get_form_class()
            form_name = 'form'

        elif 'form1' in request.POST:
            form_class = self.second_form_class
            form_name = 'form1'

        else:
            form_class = self.third_form_class
            form_name = 'form2'

        form = self.get_form(form_class)

        if form.is_valid():
            cd = form.cleaned_data

            if 'form' in request.POST:
                form.instance.some_field = cd.get('some_field', None)
                form.instance.metadata['some_meta_field'] = cd.get('some_meta_field', None)
                form.instance.metadata['some_meta_field'] = cd.get('some_meta_field', None)

            result = super().form_valid(form)

            if form.changed_data:
                self.object.reindex()

                if 'some_image_1' in form.changed_data:
                    self.object.upload_images('some_image_1')

                if 'some_image_2' in form.changed_data:
                    self.object.upload_images('some_image_2')

            return result
        else:
            return self.form_invalid(**{form_name: form})