Question

class Thread(db.Model):
  members = db.StringListProperty()

  def user_is_member(self, user):
    return str(user) in self.members

和

thread = Thread.get(db.Key.from_path('Thread', int(id)))
is_member = thread.user_is_member(user)

但错误是：

Traceback (most recent call last):
  File "D:\Program Files\Google\google_appengine\google\appengine\ext\webapp\__init__.py", line 511, in __call__
    handler.get(*groups)
  File "D:\Program Files\Google\google_appengine\google\appengine\ext\webapp\util.py", line 62, in check_login
    handler_method(self, *args)
  File "D:\zjm_code\forum_blog_gae\main.py", line 222, in get
    is_member = thread.user_is_member(user)
AttributeError: 'NoneType' object has no attribute 'user_is_member'

为什么？

感谢

Answer 1

您正在尝试按键获取实体，但不存在具有该键的实体，因此.get（）返回None。在尝试对其执行操作之前，您需要检查是否已返回有效实体，如下所示：

thread = Thread.get(db.Key.from_path('Thread', int(id)))
if thread:
  is_member = thread.user_is_member(user)
else:
  is_member = False

或等同于：

thread = Thread.get(db.Key.from_path('Thread', int(id)))
is_member = thread.user_is_member(user) if thread else False

gae错误：AttributeError：'NoneType'对象没有属性'user_is_member'

1 个答案: