クエリで fetch_async() を使用すると、初回実行時に AssertionError でクラッシュします。すぐに再実行すれば問題ありません。
例えば。
モデルと:
class User(ndb.Model):
user = ndb.UserProperty()
name = ndb.StringProperty()
penname = ndb.StringProperty()
first_login = ndb.DateTimeProperty(auto_now_add=True)
contact = ndb.BooleanProperty()
以下はすぐに機能し、空のリストを返します。
users = User.query(User.penname == "asdf").fetch()
しかし、これはクラッシュします:
future = User.query(User.penname == "asdf").fetch_async()
users = future.get_result()
と：
Traceback (most recent call last):
File "/opt/google-appengine-python/google/appengine/ext/admin/__init__.py", line 320, in post
exec(compiled_code, globals())
File "<string>", line 6, in <module>
File "/opt/google-appengine-python/google/appengine/ext/ndb/tasklets.py", line 320, in get_result
self.check_success()
File "/opt/google-appengine-python/google/appengine/ext/ndb/tasklets.py", line 357, in _help_tasklet_along
value = gen.throw(exc.__class__, exc, tb)
File "/opt/google-appengine-python/google/appengine/ext/ndb/query.py", line 887, in _run_to_list
batch = yield rpc
File "/opt/google-appengine-python/google/appengine/ext/ndb/tasklets.py", line 435, in _on_rpc_completion
result = rpc.get_result()
File "/opt/google-appengine-python/google/appengine/api/apiproxy_stub_map.py", line 592, in get_result
return self.__get_result_hook(self)
File "/opt/google-appengine-python/google/appengine/datastore/datastore_query.py", line 2386, in __query_result_hook
self._batch_shared.conn.check_rpc_success(rpc)
File "/opt/google-appengine-python/google/appengine/datastore/datastore_rpc.py", line 1191, in check_rpc_success
rpc.check_success()
File "/opt/google-appengine-python/google/appengine/api/apiproxy_stub_map.py", line 558, in check_success
self.__rpc.CheckSuccess()
File "/opt/google-appengine-python/google/appengine/api/apiproxy_rpc.py", line 156, in _WaitImpl
self.request, self.response)
File "/opt/google-appengine-python/google/appengine/api/datastore_file_stub.py", line 568, in MakeSyncCall
response)
File "/opt/google-appengine-python/google/appengine/api/apiproxy_stub.py", line 87, in MakeSyncCall
method(request, response)
File "/opt/google-appengine-python/google/appengine/datastore/datastore_stub_util.py", line 2367, in UpdateIndexesWrapper
self._UpdateIndexes()
File "/opt/google-appengine-python/google/appengine/datastore/datastore_stub_util.py", line 2656, in _UpdateIndexes
self._index_yaml_updater.UpdateIndexYaml()
File "/opt/google-appengine-python/google/appengine/datastore/datastore_stub_index.py", line 244, in UpdateIndexYaml
all_indexes, manual_indexes)
File "/opt/google-appengine-python/google/appengine/datastore/datastore_stub_index.py", line 85, in GenerateIndexFromHistory
required, kind, ancestor, props, num_eq_filters = datastore_index.CompositeIndexForQuery(query)
File "/opt/google-appengine-python/google/appengine/datastore/datastore_index.py", line 424, in CompositeIndexForQuery
assert filter.property(0).name() == ineq_property
AssertionError
しかし、たとえば次のようにして、すぐに再度実行すると：
future = User.query(User.penname == "asdf").fetch_async()
try:
users = future.get_result()
except:
users = future.get_result()
できます。
これはいたるところで発生しており、根本的な原因を突き止めるのに苦労しています。