Проблема загрузки нескольких файлов в Django

У меня возникает ошибка, когда я пытаюсь загрузить несколько файлов в форму.
вот моя модель:

class Delivery(models.Model):
    user = models.ForeignKey(
        Client, on_delete=models.CASCADE, verbose_name=_("Client"), related_name=_("delivery_user")
    )
    pickup_address = models.ForeignKey(Address, on_delete=models.CASCADE, related_name=_("pickup_address"))
    destination_address = models.ForeignKey(Address, on_delete=models.CASCADE, related_name=_("destination_address"))
    operation_date = models.DateField(
        _("desired pickup date"), auto_now=False, auto_now_add=False, blank=False, null=False
    )
    operation_time = models.TimeField(
        _("desired pickup date"), auto_now=False, auto_now_add=False, blank=False, null=False
    )
    document = models.FileField(
        help_text=_("Delivery Documets"),
        verbose_name=_("Delivery Certificates"),
        upload_to="documents/deliveries_documents/",
        blank=True,
        null=True,
    )

    class Meta:
        ordering = ("-created_at",)
        verbose_name = _("Delivery")
        verbose_name_plural = _("Deliveries")

    def get_absolute_url(self):
        return reverse("delivery:unconf-delivery-details", args=[self.id])

Я использовал пример с сайта Django для обработки множественной загрузки файлов, и вот форма и представление для этой модели:
View.py

class DeliveryCreateView(LoginRequiredMixin, UserPassesTestMixin, CreateView, FormView):
    model = Delivery
    form_class = UserDeliveryForm
    template_name = "deliveries/customer/edit_deliveries.html"

    def get_success_url(self):
        return reverse("delivery:operation-form", kwargs={"pk": self.object.pk})

    def test_func(self):
        return self.request.user.is_active

    def post(self, request, *args, **kwargs):
        form_class = self.get_form_class()
        form = self.get_form(form_class)
        files = request.FILES.getlist("decument")
        if form.is_valid():
            for file in files:
                self.Delivery.objects.create(document=file)
            return self.form_valid(form)
        else:
            return self.form_invalid(form)

Form.py

class UserDeliveryForm(forms.ModelForm):
    class Meta:
        model = Delivery
        fields = [
            "user",
            "pickup_address",
            "destination_address",
            "operation_date",
            "operation_time",
            "document",
        ]
        widgets = {
            "operation_date": forms.DateInput(
                format=("%d %B %Y"),
                attrs={"class": "form-control mb-2 delivery-form", "placeholder": "JJ-MM-AAAA"},
            ),
            "operation_time": forms.TimeInput(
                attrs={"type": "time", "class": "form-control mb-2 delivery-form"},
            ),
            "document": forms.ClearableFileInput(attrs={"multiple": True}),
            "user": forms.Select(),
            "pickup_address": forms.Select(),
            "destination_address": forms.Select(),
        }

    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        self.fields["user"].widget.attrs.update({"class": "form-control mb-2 delivery-form", "Placeholder": "Client "})
        self.fields["pickup_address"].widget.attrs.update(
            {"class": "form-control mb-2 dropdown delivery-form", "Placeholder": "Addresse de ramassage "}
        )
        self.fields["destination_address"].widget.attrs.update(
            {"class": "form-control mb-2 delivery-form", "Placeholder": "Addresse de destination"}
        )
        self.fields["document"].widget.attrs.update(
            {"class": "form-control mb-2 delivery-form", "Placeholder": "document"}
        )

когда я тестирую форму, я получаю эту ошибку:
AttributeError at /delivery/new_delivery У объекта 'DeliveryCreateView' нет атрибута 'object'. Я не знаю, в чем именно проблема, файл, который я пытался загрузить - это несколько картинок *.jpg.

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