关于mongodb创建数据库失败的问题

至尊小宝 2017-10-27 05:57:57

# -*-coding:utf-8 -*-

from datetime import datetime,timedelta, date

from pymongo import MongoClient



class MongoCache:

    def __init__(self,client=None,expires=timedelta(days=30)):

        self.client=MongoClient('localhost',27017) if client is None else client

        self.db=client.cache#这个位置出错啊！！！！！

        self.db.webpage.create_index('timestamp',expiresAfterSeconds=expires.total_seconds())

        print expires.total_seconds()

        

    def __getitem__(self,url):

        record=self.db.webpage.find_one({'id':url})

        if record:

            return record['result']

        else:

            raise KeyError(url+' doed not exit')

        

    def __setitem__(self,url,result):

        record={'result':result,'timestamp':datetime.utcnow()}

        self.db.webpage.update({'_id':url},{'$set':record},upsert=True)

        

if __name__=='__main__':

    url='http://baidu.com'

    cache=MongoCache(expires=timedelta())

    result={'html':'test test test!!!'}

    cache[url]=result

    print cache[url]

上面的代码我是想做一个缓存机制来的，可为什么运行的时候连MongoCache对象都不能创建？
错误提示：

Traceback (most recent call last):

  File "D:\Project\core3\src\coremongotest1.py", line 25, in <module>

    cache=MongoCache(expires=timedelta())

  File "D:\Project\core3\src\coremongotest1.py", line 8, in __init__

    self.db=client.cache

AttributeError: 'NoneType' object has no attribute 'cache'

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