Question

当我尝试一些抓取代码时遇到了这个问题。我定义了一个MongoCache类来缓存html页面：

class MongoCache:
    def __init__(self, client=None, expires=timedelta(days=30)):
        self.client = MongoClient('localhost', 27017) if client is None else client
        self.db = self.client.cache
        self.db.webpage.create_index('timestamp1', expireAfterSeconds=expires.total_seconds())

当我构建对象时：

cache = MongoCache()

出现故障信息。

Traceback (most recent call last):
  File "<input>", line 1, in <module>
  File "F:\pythoncode\webscraping\mongo_cache.py", line 20, in __init__
  File "D:\python27\lib\site-packages\pymongo\collection.py", line 1958, in create_index
self.__create_index(keys, kwargs, session, **cmd_options)
  File "D:\python27\lib\site-packages\pymongo\collection.py", line 1860, in __create_index
session=session)
  File "D:\python27\lib\site-packages\pymongo\collection.py", line 244, in _command
retryable_write=retryable_write)
  File "D:\python27\lib\site-packages\pymongo\pool.py", line 579, in command
unacknowledged=unacknowledged)
  File "D:\python27\lib\site-packages\pymongo\network.py", line 150, in command
parse_write_concern_error=parse_write_concern_error)
  File "D:\python27\lib\site-packages\pymongo\helpers.py", line 155, in _check_command_response
  raise OperationFailure(msg % errmsg, code, response)
  OperationFailure: Index with name: timestamp_1 already exists with different options

我尝试了stackoverflow的一些解决方案，但这些解决方案不适用于pymongo，甚至无法使用drop_index（）方法。我在pycharm上使用了win10，python2.7，而MongoDB服务器版本为4.0.3。我花了两天时间来解决问题，然后放弃了。

Answer 1

现在，我再次尝试了该问题，发现问题可能出在用于索引的时间戳记中。我定义了一个没有输入参数的对象，一切正常。

cache = MongoCache()

但是，使用时间戳记，它又出现了：

cache = MongoCache(expires=timedelta())

保存url值的功能是：

def __setitem__(self, url, result):
    record = {
        'result': Binary(zlib.compress(pickle.dumps(result))), 
        'timestamp': datetime.utcnow()}
    self.db.webpage.update({'_id': url}, {'$set': record}, upsert=True)

Pymongo OperationFailure：名称为：timestamp_1的索引已经存在，具有不同的选项

1 个答案: