为什么我一直获取名称错误：名称“PS”未定义

Question

好吧，在我的模型.py我刚创建的文件：

class PL(models.Model):
  created = models.DateTimeField(default=timezone.now)
  owner = models.ForeignKey(User, related_name='PL')
  text = models.CharField(max_length=2000, blank=True)
  rating = models.IntegerField(default=0)
  pal = models.ManyToManyField(PS, blank=True, null=True)
  class Meta:
    verbose_name = "PL text"
  def __unicode__(self):
    return self.user

class PS(models.Model):
  Original = models.ForeignKey(PL, related_name='OPL', blank=True)
  rating = models.IntegerField(default=0)
  word = models.CharField(max_length=50, blank=True)

  def __unicode__(self):
    return "Word: %s" % (self.word)

但是我一直得到：NameError:name'PS'没有定义

为什么会这样？在

Answer 1

就像mgilson说的，这是自上而下的。但是Django有办法克服它-

pal = models.ManyToManyField('PS', blank=True, null=True)

Django doc在ForeignKey下描述了它。在

If you need to create a relationship on a model that has not yet been defined, you can use the name of the model, rather than the model object itself.

你可以read more here。在