Question

我正在使用django 1.4，我有以下型号：

class Newsletter(EmailTemplate):
    receivers = models.ManyToManyField(User, related_name='newsletters',
                                       db_index=True,
                                       through='NewsletterReceiver')

class EmailReceiver(models.Model):
    user = models.ForeignKey(User, db_index=True)

class NewsletterReceiver(EmailReceiver):
    newsletter = models.ForeignKey(Newsletter, db_index=True)

当我在我的视图中通过执行以下操作创建Newsletter对象时：

newsletter = form.save(commit=False)
newsletter.receivers.clear()
receivers = form.cleaned_data['receivers']
for receiver in receivers:
    newsletter_receiver = NewsletterReceiver(user=receiver, newsletter=newsletter)
    newsletter_receiver.save()

form.save_m2m()
newsletter.save()

我可以看到Newsletter对象和NewsletterReceiver对象都已创建。如果我从新创建的ipython查询user和newsletter，则使用NewsletterReceiver一切正常，但如果我从Newsletter实例查询接收器然后django抱怨我不明白的事情：

In [2]: nr = NewsletterReceiver.objects.all()[0]

In [3]: nr.user
Out[3]: <User: 3>

In [4]: nr.newsletter
Out[4]: <Newsletter: Newsletter object>

In [5]: nr.newsletter.receivers
Out[5]: <django.db.models.fields.related.ManyRelatedManager at 0x10ea26f90>

In [6]: nr.newsletter.receivers.all()
Out[6]: 
<repr(<django.db.models.query.QuerySet at 0x10ee860d0>) failed:
django.db.utils.DatabaseError: column web_newsletterreceiver.user_id does not exist
LINE 1: ...N "web_newsletterreceiver" ON ("auth_user"."id" = "web_newsl...
                                                         ^
>

这是因为目标模型的ForeignKey是继承的吗？是否有解决方法或我是否必须重构模型？

Answer 1

如果有one2many，

primary_key关系将成为可能。就像你加入2个表一样，你必须按连接顺序给出primary_key。

请在模型中添加一个主键。

当您尝试使用all()函数检索数据时，它会尝试加入主键。

Answer 2

我通过添加：

解决了这个问题

class Meta:
    abstract = True

到EmailReceiver模型。

Django - 在中间表中是否可以将继承的ForeignKey用于目标模型？

2 个答案: