python之如何在 Datastore Plus(NDB) 中查询 Model.KeyProperty == None

假设一个 NDB(版本 0.7 和 0.8)模型，其键可以是 None:

class Test(model.Model): 
    k = model.KeyProperty() 
    value = model.IntegerProperty() 
 
 count = Test.query(Test.k == None).count() # error 
 #count = Test.query(Test.k != None).count() # error also 

只有使用 None 过滤键才会抛出错误。

File "/Applications/GoogleAppEngineLauncher.app/Contents/Resources/GoogleAppEngine-default.bundle/Contents/Resources/google_appengine/google/appengine/ext/webapp/_webapp25.py", line 701, in __call__ 
    handler.get(*groups) 
File "/Users/reiot/Documents/Works/ndbtest/main.py", line 91, in get 
    count = Test.query(Test.k == None).count() # error 
File "/Users/reiot/Documents/Works/ndbtest/ndb/model.py", line 500, in __eq__ 
    return self._comparison('=', value) 
File "/Users/reiot/Documents/Works/ndbtest/ndb/model.py", line 491, in _comparison 
    return FilterNode(self._name, op, self._datastore_type(value)) 
File "/Users/reiot/Documents/Works/ndbtest/ndb/model.py", line 1138, in _datastore_type 
    return datastore_types.Key(value.urlsafe()) 
AttributeError: 'NoneType' object has no attribute 'urlsafe' 

如何使用 None 查询 KeyProperty？

请您参考如下方法:

这看起来像是 NDB 中的一个错误。你能在问题跟踪器上提交一份吗？