App Engine下载有限数量的实体

Question

我想下载有限数量的应用引擎实体，比如说只有500个。是否可以通过Python bulkloader API执行此操作？

Answer 1

AFAIK bulkloader API旨在获取给定种类的所有实体或所有实体。

如果要下载500个特定实体，可以依赖远程API远程访问数据存储区，如this article

中所述

Answer 2

在不下载所有实体的情况下调试转换失败非常有用。这是我对bulkloader的修改，基于1.6.4 SDK：

diff -r 1/google/appengine/tools/appcfg.py 2/google/appengine/tools/appcfg.py
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>                      'limit',
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>     parser.add_option('--limit', type='int', dest='limit',
>                       action='store', default=None,
>                       help='Number of records to download (for debugging).')
diff -r 1/google/appengine/tools/bulkloader.py 2/google/appengine/tools/bulkloader.py
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                throttle_class=None,
>                limit=None):
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>     if limit != None:
>         logger.info("Aborting download after downloading %s entities" % limit)
>     self.limit_cnt = limit
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>       if self.limit_cnt and self.limit_cnt <= 0:
>         logger.info("Reached limit, abort downloading more entities")
>         return []
>
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>       self.limit_cnt = self.limit_cnt - len(results)
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       while result_pb.more_results() and self.limit_cnt > 0:
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>     self.limit = arg_dict['limit']
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                                                         self.throttle_class,
>                                                         self.limit)
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             'rps_limit', 'limit')
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>   arg_dict['limit'] = None