Question

这个看似完美的Google App Engine代码因KindError而失败。

# in a django project 'stars'
from google.appengine.ext import db

class User(db.Model):
    pass

class Picture(db.Model):
    user = db.ReferenceProperty(User)

user = User()
user.put()

picture = Picture()
picture.user = user
# ===> KindError: Property user must be an instance of stars_user

google.appengine.ext.db.ReferenceProperty.validate中引发了异常：

def validate(self, value):
    ...
    if value is not None and not isinstance(value, self.reference_class):
      raise KindError('Property %s must be an instance of %s' %
                            (self.name, self.reference_class.kind()))
    ...

Answer 1

原来我在admin.py中导入模型为

from frontend.stars.models import Star

此行污染了Star的模块名称空间，isinstance查询失败。

>>> user.__class__
<class 'frontend.stars.models.User'>
>>> Picture.user.reference_class
<class 'stars.models.User'>

有关设置ReferenceProperty值的KindError

1 个答案: