App Engine的开发环境 - db.get方法（）的ReferenceProperty查询随机误差

Question

我有以下的数据存储模式：

class FeatureCategory(db.Model): 
    name_eng = db.StringProperty(required=True) 
    name_spa = db.StringProperty() 
    name_por = db.StringProperty() 
    device_type = db.ReferenceProperty(DeviceType, required=True, collection_name='feature_categories') 

class Feature(db.Model): 
    name = db.StringProperty(required=True) 
    category = db.ReferenceProperty(FeatureCategory, required=True, collection_name='features') 
    desc_eng = db.StringProperty() 
    desc_spa = db.StringProperty() 
    desc_por = db.StringProperty() 

我已经遇到错误时做了几个分贝之后。获取（db.Key（'key_string'））和参考对象，如：

feats = dbmodel.Feature.all() 
for feat in feats: 
    cat = feat.category 

在开发环境中。如果我停止服务器并重新启动，它将适用于某些查询，并回到抛出下面的错误。任何想法如何解决这个问题？

Traceback (most recent call last): 
    File "/Applications/Development/GoogleAppEngineLauncher.app/Contents/Resources/GoogleAppEngine-default.bundle/Contents/Resources/google_appengine/lib/webapp2/webapp2.py", line 1536, in __call__ 
    rv = self.handle_exception(request, response, e) 
    File "/Applications/Development/GoogleAppEngineLauncher.app/Contents/Resources/GoogleAppEngine-default.bundle/Contents/Resources/google_appengine/lib/webapp2/webapp2.py", line 1530, in __call__ 
    rv = self.router.dispatch(request, response) 
    File "/Applications/Development/GoogleAppEngineLauncher.app/Contents/Resources/GoogleAppEngine-default.bundle/Contents/Resources/google_appengine/lib/webapp2/webapp2.py", line 1278, in default_dispatcher 
    return route.handler_adapter(request, response) 
    File "/Applications/Development/GoogleAppEngineLauncher.app/Contents/Resources/GoogleAppEngine-default.bundle/Contents/Resources/google_appengine/lib/webapp2/webapp2.py", line 1102, in __call__ 
    return handler.dispatch() 
    File "/Applications/Development/GoogleAppEngineLauncher.app/Contents/Resources/GoogleAppEngine-default.bundle/Contents/Resources/google_appengine/lib/webapp2/webapp2.py", line 572, in dispatch 
    return self.handle_exception(e, self.app.debug) 
    File "/Applications/Development/GoogleAppEngineLauncher.app/Contents/Resources/GoogleAppEngine-default.bundle/Contents/Resources/google_appengine/lib/webapp2/webapp2.py", line 570, in dispatch 
    return method(*args, **kwargs) 
    File "/Users/danielgarcia/Documents/workspace/rfpbuilder/src/get.py", line 50, in get 
    cat = feat.category 
    File "/Applications/Development/GoogleAppEngineLauncher.app/Contents/Resources/GoogleAppEngine-default.bundle/Contents/Resources/google_appengine/google/appengine/ext/db/__init__.py", line 3686, in __get__ 
    instance = get(reference_id) 
    File "/Applications/Development/GoogleAppEngineLauncher.app/Contents/Resources/GoogleAppEngine-default.bundle/Contents/Resources/google_appengine/google/appengine/ext/db/__init__.py", line 1536, in get 
    return get_async(keys, **kwargs).get_result() 
    File "/Applications/Development/GoogleAppEngineLauncher.app/Contents/Resources/GoogleAppEngine-default.bundle/Contents/Resources/google_appengine/google/appengine/api/apiproxy_stub_map.py", line 592, in get_result 
    return self.__get_result_hook(self) 
    File "/Applications/Development/GoogleAppEngineLauncher.app/Contents/Resources/GoogleAppEngine-default.bundle/Contents/Resources/google_appengine/google/appengine/datastore/datastore_rpc.py", line 1467, in __get_hook 
    entities = rpc.user_data(entities) 
    File "/Applications/Development/GoogleAppEngineLauncher.app/Contents/Resources/GoogleAppEngine-default.bundle/Contents/Resources/google_appengine/google/appengine/api/datastore.py", line 600, in local_extra_hook 
    return extra_hook(result) 
    File "/Applications/Development/GoogleAppEngineLauncher.app/Contents/Resources/GoogleAppEngine-default.bundle/Contents/Resources/google_appengine/google/appengine/ext/db/__init__.py", line 1506, in extra_hook 
    model = cls1.from_entity(entity) 
    File "/Applications/Development/GoogleAppEngineLauncher.app/Contents/Resources/GoogleAppEngine-default.bundle/Contents/Resources/google_appengine/google/appengine/ext/db/__init__.py", line 1441, in from_entity 
    return cls(None, _from_entity=entity, **entity_values) 
    File "/Applications/Development/GoogleAppEngineLauncher.app/Contents/Resources/GoogleAppEngine-default.bundle/Contents/Resources/google_appengine/google/appengine/ext/db/__init__.py", line 973, in __init__ 
    prop.__set__(self, value) 
    File "/Applications/Development/GoogleAppEngineLauncher.app/Contents/Resources/GoogleAppEngine-default.bundle/Contents/Resources/google_appengine/google/appengine/ext/db/__init__.py", line 613, in __set__ 
    value = self.validate(value) 
    File "/Applications/Development/GoogleAppEngineLauncher.app/Contents/Resources/GoogleAppEngine-default.bundle/Contents/Resources/google_appengine/google/appengine/ext/db/__init__.py", line 2815, in validate 
    value = super(StringProperty, self).validate(value) 
    File "/Applications/Development/GoogleAppEngineLauncher.app/Contents/Resources/GoogleAppEngine-default.bundle/Contents/Resources/google_appengine/google/appengine/ext/db/__init__.py", line 640, in validate 
    raise BadValueError('Property %s is required' % self.name) 
BadValueError: Property name is required 

Answer 1

请下次缩进代码。错误消息Property name is required表示某个Feature实体没有name属性，该属性在模型中标记为需要。