models.py

Question

保存具有ForeignKey的对象时，我收到常见错误： '无法分配“（myObject）”：“（我的ForeignKey字段）”必须是实例'。

这个问题得到了明确答复：

Django - Foreign Key must be an instance

但解决方案对我不起作用。

models.py

class User(models.Model):
  email = models.EmailField(max_length=100, unique=True)
  password = models.CharField(validators=[MinLengthValidator(8)],max_length=60)
  is_teacher = models.BooleanField(default=0)


class Question(models.Model):
  question_text = models.CharField(max_length=5000)
  pub_date = models.DateTimeField('date asked')
  answered = models.BooleanField(default=False)
  asker = models.IntegerField(default=0)
  def __str__(self):
    return self.question_text
  def was_published_recently(self):
    now = timezone.now()
    return now - datetime.timedelta(days=1) <= self.pub_date <= now;
  def asked_by(self):
    return self.asker

class Answer(models.Model):
  to_question = ForeignKey(Question, null=False)
  pub_date = models.DateTimeField('date answered')
  answer_text = models.CharField(max_length=10000)
  answered_by = ForeignKey(User, null=False)
  def __str__(self):
    return self.answer_text

views.py

@staff_member_required()
def answerQuestion(request):
  if request.method == 'POST':
    form = QuestionAnswerForm(request.POST,label_suffix='',error_class=DivErrorList)
    if form.is_valid():
      answer_text = request.POST['answer_text']
      question_id = request.POST['question_id']
      now = timezone.now()
      try:
        to_question = Question.objects.get(pk=question_id)
        answered_by= User.objects.get(pk=request.user.id)
        Answer.objects.create(answer_text=answer_text, to_question=to_question, pub_date=now, answered_by=answered_by)
        return render(request, 'askWisdom/answerQuestion.html', { 'result':'Thanks for Your Answer' })
      except Question.DoesNotExist:
        return HttpResponse("Question doesn't exist.")
      except User.DoesNotExist:
        return HttpResponse("Answering User doesn't exist.")

    else:
      return render(request, 'askWisdom/answerQuestion.html', {'form': form, 'error_message': form.errors })

实际错误是： '无法分配“用户：sampleUser@gmail.com”：“Answer.answered_by”必须是“用户”实例'。

奇怪的是，我的答案模型有两个ForeignKeys，但在做的时候

Answer.objects.create(answer_text=answer_text, to_question=to_question, pub_date=now, answered_by=answered_by)

错误在第二个ForeignKey（answers_by = answers_by）上标记，但不是第一个（to_question = to_question），假设它们按顺序处理。

好的，所以更改它以强制在数据库级别保存数字ID：

answered_by_id= User.objects.get(pk=request.user.id).id
Answer.objects.create(answer_text=answer_text, to_question=to_question, pub_date=now, answered_by_id=answered_by_id)

我收到错误： 'column answer.id不存在'

在这种情况下，Postgres数据库中有一个名为answers_by_id的实际列，所以我不明白为什么它会寻找一个隐藏的，显然是自动生成的'answer.id'列。

但无论如何，我宁愿让默认方法将实例传递给ForeignKey字段。

我有什么明显的东西可以忽略吗？如果它只是一个错字，我会感到尴尬。

Answer 1

除非您设置了自定义用户模型，否则request.user将是django.contrib.auth.models.User个实例，与您的User模型不同。你不应该用这样的密码字段创建自己的模型，这是不安全的。

将ForeignKey保存为实例，但无论如何都会抱怨

models.py

views.py

1 个答案: