在没有模型的情况下在数据存储中查询

Question

我正在尝试在 appengine 中创建一个搜索键列表的应用程序，然后我使用此列表从数据存储中删除这些记录，此服务必须是通用服务，因此我无法使用模型只需按种类名称搜索，是否可以通过应用程序引擎功能进行搜索？

在我的代码下面，但它需要我有一个模型。

导入httplib 导入日志从日期时间导入日期时间，timedelta

import webapp2
from google.appengine.api import urlfetch
from google.appengine.ext import ndb

DEFAULT_PAGE_SIZE = 100000
DATE_PATTERN = "%Y-%m-%dT%H:%M:%S"


def get_date(amount):
    date = datetime.today() - timedelta(days=30 * amount)
    date = date.replace(hour=0, minute=0, second=0)
    return date


class Purge(webapp2.RequestHandler):

    def get(self):
        kind = self.request.get('kind')
        datefield = self.request.get('datefield')
        amount = self.request.get('amount', default_value=3)
        date = get_date(amount)

        logging.info('Executando purge para Entity {}, mantendo periodo de {} meses.'.format(kind, amount))

        # cria a query
        query = ndb.Query(kind=kind, namespace='development')

        logging.info('Setando o filtro [{} <= {}]'.format(datefield, date.strftime(DATE_PATTERN)))

        # cria um filtro
        query.filter(ndb.DateTimeProperty(datefield) <= date)

        query.fetch_page(DEFAULT_PAGE_SIZE)

        while True:
            # executa a consulta
            keys = query.fetch(keys_only=True)

            logging.info('Encontrados {} {} a serem exluidos'.format(len(keys), kind))

            # exclui usando as keys
            ndb.delete_multi(keys)

            if len(keys) < DEFAULT_PAGE_SIZE:
                logging.info('Nao existem mais registros a serem excluidos')
                break


app = webapp2.WSGIApplication(
    [
        ('/cloud-datastore-purge', Purge),
    ], debug=True)

追踪

Traceback (most recent call last):
  File "/base/alloc/tmpfs/dynamic_runtimes/python27g/7894e0c59273b2b7/python27/python27_lib/versions/third_party/webapp2-2.5.2/webapp2.py", line 1535, in __call__
    rv = self.handle_exception(request, response, e)
  File "/base/alloc/tmpfs/dynamic_runtimes/python27g/7894e0c59273b2b7/python27/python27_lib/versions/third_party/webapp2-2.5.2/webapp2.py", line 1529, in __call__
    rv = self.router.dispatch(request, response)
  File "/base/alloc/tmpfs/dynamic_runtimes/python27g/7894e0c59273b2b7/python27/python27_lib/versions/third_party/webapp2-2.5.2/webapp2.py", line 1278, in default_dispatcher
    return route.handler_adapter(request, response)
  File "/base/alloc/tmpfs/dynamic_runtimes/python27g/7894e0c59273b2b7/python27/python27_lib/versions/third_party/webapp2-2.5.2/webapp2.py", line 1102, in __call__
    return handler.dispatch()
  File "/base/alloc/tmpfs/dynamic_runtimes/python27g/7894e0c59273b2b7/python27/python27_lib/versions/third_party/webapp2-2.5.2/webapp2.py", line 572, in dispatch
    return self.handle_exception(e, self.app.debug)
  File "/base/alloc/tmpfs/dynamic_runtimes/python27g/7894e0c59273b2b7/python27/python27_lib/versions/third_party/webapp2-2.5.2/webapp2.py", line 570, in dispatch
    return method(*args, **kwargs)
  File "/base/data/home/apps/p~telefonica-dev-155211/cloud-datastore-purge-python:20180629t150020.410785498982375644/purge.py", line 38, in get
    query.fetch_page(_DEFAULT_PAGE_SIZE)
  File "/base/alloc/tmpfs/dynamic_runtimes/python27g/7894e0c59273b2b7/python27/python27_lib/versions/1/google/appengine/ext/ndb/utils.py", line 160, in positional_wrapper
    return wrapped(*args, **kwds)
  File "/base/alloc/tmpfs/dynamic_runtimes/python27g/7894e0c59273b2b7/python27/python27_lib/versions/1/google/appengine/ext/ndb/query.py", line 1362, in fetch_page
    return self.fetch_page_async(page_size, **q_options).get_result()   
  File "/base/alloc/tmpfs/dynamic_runtimes/python27g/7894e0c59273b2b7/python27/python27_lib/versions/1/google/appengine/ext/ndb/tasklets.py", line 383, in get_result
    self.check_success()
  File "/base/alloc/tmpfs/dynamic_runtimes/python27g/7894e0c59273b2b7/python27/python27_lib/versions/1/google/appengine/ext/ndb/tasklets.py", line 427, in _help_tasklet_along
    value = gen.throw(exc.__class__, exc, tb)
  File "/base/alloc/tmpfs/dynamic_runtimes/python27g/7894e0c59273b2b7/python27/python27_lib/versions/1/google/appengine/ext/ndb/query.py", line 1380, in _fetch_page_async
    while (yield it.has_next_async()):
  File "/base/alloc/tmpfs/dynamic_runtimes/python27g/7894e0c59273b2b7/python27/python27_lib/versions/1/google/appengine/ext/ndb/tasklets.py", line 427, in _help_tasklet_along
    value = gen.throw(exc.__class__, exc, tb)
  File "/base/alloc/tmpfs/dynamic_runtimes/python27g/7894e0c59273b2b7/python27/python27_lib/versions/1/google/appengine/ext/ndb/query.py", line 1793, in has_next_async
    yield self._fut
  File "/base/alloc/tmpfs/dynamic_runtimes/python27g/7894e0c59273b2b7/python27/python27_lib/versions/1/google/appengine/ext/ndb/context.py", line 890, in helper
    batch, i, ent = yield inq.getq()
  File "/base/alloc/tmpfs/dynamic_runtimes/python27g/7894e0c59273b2b7/python27/python27_lib/versions/1/google/appengine/ext/ndb/query.py", line 969, in run_to_queue
    batch = yield rpc
  File "/base/alloc/tmpfs/dynamic_runtimes/python27g/7894e0c59273b2b7/python27/python27_lib/versions/1/google/appengine/ext/ndb/tasklets.py", line 513, in _on_rpc_completion
    result = rpc.get_result()
  File "/base/alloc/tmpfs/dynamic_runtimes/python27g/7894e0c59273b2b7/python27/python27_lib/versions/1/google/appengine/api/apiproxy_stub_map.py", line 613, in get_result
    return self.__get_result_hook(self)
  File "/base/alloc/tmpfs/dynamic_runtimes/python27g/7894e0c59273b2b7/python27/python27_lib/versions/1/google/appengine/datastore/datastore_query.py", line 2951, in __query_result_hook
    self.__results = self._process_results(query_result.result_list())
  File "/base/alloc/tmpfs/dynamic_runtimes/python27g/7894e0c59273b2b7/python27/python27_lib/versions/1/google/appengine/datastore/datastore_query.py", line 2984, in _process_results
    for result in results]
  File "/base/alloc/tmpfs/dynamic_runtimes/python27g/7894e0c59273b2b7/python27/python27_lib/versions/1/google/appengine/datastore/datastore_rpc.py", line 194, in pb_to_query_result
    return self.pb_to_entity(pb)
  File "/base/alloc/tmpfs/dynamic_runtimes/python27g/7894e0c59273b2b7/python27/python27_lib/versions/1/google/appengine/ext/ndb/model.py", line 690, in pb_to_entity
    modelclass = Model._lookup_model(kind, self.default_model)
  File "/base/alloc/tmpfs/dynamic_runtimes/python27g/7894e0c59273b2b7/python27/python27_lib/versions/1/google/appengine/ext/ndb/model.py", line 3101, in _lookup_model
    kind)
KindError: No model class found for kind 'Test'. Did you forget to import it?

Answer 1

在设置fetch_page的那一行发现了问题。

删除此行

query.fetch_page(DEFAULT_PAGE_SIZE)

为此

keys = query.fetch(limit=_DEFAULT_LIMIT, keys_only=True)

Answer 2

要运行环境中没有可用模型 class 的数据存储区查询，您可以使用 google.appengine.api.datastore.Query class from the low-level datastore API。

有关其他想法，请参阅。

Answer 3

如果目标只是擦除实体而不考虑其种类，那么除了您自己指定 kinds/models 之外，您还有一些选择。

您可以从您的模型文件中获取各种类型的列表并遍历它们，请参阅How to delete all the entries from google datastore?
使用通用数据存储客户端库（不是 ndb），您可以从数据存储本身获取种类列表，请参阅但我依稀记得一些问题可能转化为该库不再适用于第一代标准环境，所以我不能 100% 确定这一点。

在没有模型的情况下在数据存储中查询

query in datastore without a model

google-app-engine

python-2.7

google-app-engine-python