python - NOT NULL 约束失败 : portal_visitrequests. visitor_id

Question

我是 django 的新手，我已经为这个特定项目奋斗了一段时间。每次尝试提交表单(最终创建 Visitor 和 VisitRequests 对象)时，我都会收到一个非空约束错误。错误来自这行代码...visit_request = VisitRequests(staff=staff, visitor=visitor, comment=comment, token=token, status=None).save()... 请查看下面的代码。

views.py

def formpage(request):
    if request.method=='POST':
        token=secrets.token_urlsafe(20)
        visitor_name=request.POST.get('visitorsname')
        comment=request.POST.get('comment')
        visit_type=request.POST.get('visit_type')
        visit_content='You have a waiting visitor'+'\n'+'Name:'+visitor_name+'\n'+'Purpose Of Visit:'+visit_type+'\n'+'Additional Comment:'+comment+'\n'+token
        staff_id=request.POST.get('staff')
        staff=Staff.objects.get(id=staff_id)
        staff_email=staff.staff_email
        req_comment = request.POST.get('req_comment')
        request_id = (request.POST.get('request_id'))
        visitor=Visitor(visitor_name=visitor_name).save()
        visit_request = VisitRequests(staff=staff, visitor=visitor, comment=comment, token=token, status=None).save()

模型.py

class Staff(models.Model):
    staff_name = models.CharField(max_length=250)
    staff_email = models.CharField(max_length=250, default="")

    def __str__(self):
        return self.staff_name

class Visitor(models.Model):
    visitor_name = models.CharField(max_length=250)
    timestamp = models.DateTimeField(default=timezone.now)

    def __str__(self):
        return '{}'.format(self.visitor_name)

class VisitRequests(models.Model):
    staff=models.ForeignKey(Staff, on_delete=models.CASCADE)
    visitor = models.ForeignKey(Visitor, on_delete=models.CASCADE)
    comment= models.TextField(default='')
    status= models.NullBooleanField()
    token=models.CharField(max_length=20)

Answer 1

您的实现假设 Django 的 save 返回模型对象，但事实并非如此。您可能想阅读 Why does django ORM's save method not return the saved object?以便进一步了解。

在您的情况下，您可以使用 Django's create创建和获取返回对象的函数:

visitor = Visitor.objects.create(visitor_name=visitor_name)
visit_request = VisitRequests.objects.create(staff=staff, visitor=visitor, comment=comment, token=token, status=None)