ValueError: save() 禁止以防止由于未保存的相关对象“发件人”而导致数据丢失

Question

我正在尝试在创建报价对象时创建消息 obj。我试过查看官方的 Django 文档，但它似乎并不适用。不知道哪里出错了。

class Message(models.Model):
    sender = models.ForeignKey(User, related_name="sender_user")
    recipient = models.ForeignKey(User, related_name="recipient_user")
    sender_read = models.BooleanField(default=False)
    recipient_read = models.BooleanField(default=False)
    parent_msg = models.ForeignKey("self", null=True, blank=True, related_name="parent")
    subject  = models.CharField(max_length=255, blank=True, null=True)
    message = models.TextField(null=True, blank=True)
    created = models.DateTimeField(auto_now_add=True, null=True, blank=True)

这是我的报价表

class Quotation(models.Model):
    editor = models.ForeignKey(Editors)
    discipline = models.ForeignKey(Discipline, null=True, blank=True)
    title = models.CharField(max_length=255)
    description = models.TextField(null=True, blank=True)
    words_count = models.CharField(max_length=255)
    student = models.ForeignKey(Students, null=True, blank=True)
    created = models.DateTimeField(auto_now_add=True, null=True,   blank=True)
modified = models.DateTimeField(auto_now=True, null=True, blank=True)

这是我的视图函数：

quotation = Quotation.objects.create(
    editor=editor,
    student=student,
    title=form.cleaned_data['title'],
    discipline = discipline,
    description = form.cleaned_data['description'],
    words_count=form.cleaned_data['words_count']
)
quotation.save()

create_message = Message.objects.create(
    sender= User(username=quotation.student.user.username),
    recipient=User(username=quotation.editor.user.username),
    subject=quotation.title,
    messages=quotation.description
)

Answer 1

当你使用 Quotation.objects.create 时，Django 会自动创建并将对象保存到数据库中。因此，quotation.save() 应该被删除，因为它是不必要的。

除此之外，使用User(...) 不会将对象保存到数据库中。在插入sender 和receiver 外键的用户之前，您仍然需要调用save 或使用上述解决方案（create）。

views.py:

quotation = Quotation.objects.create(
    editor=editor,
    student=student,
    title=form.cleaned_data['title'],
    discipline = discipline,
    description = form.cleaned_data['description'],
    words_count=form.cleaned_data['words_count']
)

sender = User.objects.create(username=quotation.student.user.username)
receiver = User.objects.create(username=quotation.editor.user.username)
create_message = Message.objects.create(
    sender= sender,
    recipient=receiver,
    subject=quotation.title,
    messages=quotation.description
)