我想插入新的报价。但总是错误“无法分配“4030”：“Quotation.contact“必须是“Contact”示例。”我还想使用foreign_key，因此需要示例Contact。

class QuotationCreateView(CreateView):
    model = Quotation
    form_class = QuotationForm
    template_name = "quotation_form.html"

    def form_valid(self, form):
        contact_id = form.cleaned_data['contact']
        contact_instance = Contact.objects.get(pk=contact_id)
        self.object = form.save(commit=False)
        self.object.contact = contact_instance
        self.object.save()

        return super(QuotationCreateView, self).form_valid(form)

    def get_success_url(self):
        return reverse('quotation:list')

    def get_form_kwargs(self):
        kwargs = super().get_form_kwargs()
        username = self.request.session.get('user')['name']
        kwargs['initial'] = {'our_charge_string': username}
        return kwargs

class Quotation(models.Model):
    contact = models.ForeignKey(Contact, on_delete=models.CASCADE)
    our_charge_string = models.CharField(max_length=30)

class Contact(models.Model):
    our_charge_string = models.CharField(max_length=30, null=True)
    reception_datetime = models.DateTimeField(editable=True)

class QuotationForm(forms.ModelForm):
    contact = forms.IntegerField(label='連絡ID')
    our_charge_string = forms.CharField(label='当社担当者', max_length=30)

    class Meta:
        model = Quotation
        fields = ("contact", "our_charge_string", "car_type_string", "loading_memo_string",
                  "loading_place_string", "delivery_memo_string", "delivery_place_string", "transit_place_string",
                  "item_string", "memo_string", "customer_id",)

我在form_valid行上放了一个断点。