从MLab迭代pymongo游标
从MLab迭代pymongo游标
提问于 2016-08-24 15:25:13
为什么游标不会迭代？我确信应该有一个简单的解决方案。
我已经尝试了多个堆栈溢出答案和Mongodb https://docs.mongodb.com/getting-started/python/query/的文档
代码如下：
from pymongo import MongoClient
#Connect to Mongo Client
client = MongoClient('mongodb://the_username:the_password@ds047124.mlab.com:47124/politicians_from_theage')
db = client.politicians_from_theage #define database used
# Define Collection
collection = db.posts
print collection结果：
Collection(Database(MongoClient(host=['ds047124.mlab.com:47124'], document_class=dict, tz_aware=False, connect=True), u'politicians_from_theage'), u'posts')然后光标将打印其位置：
# Define Cursor
my_cursor = collection.find()
print my_cursor 结果：
<pymongo.cursor.Cursor object at 0x0000000003247518>然后，尝试在游标上迭代会提供一个超时：
# Perform query
cursor = db.posts.find()
#Iterate the cursor and print the documents.
for document in cursor:
print(document) #No Luck回溯错误或迭代：
Traceback (most recent call last):
File "C:\PythonC\PythonWebScraping\17_MongoInterface\mongoget.py", line 18, in <module>
for result_object in my_cursor:
File "C:\Python27\lib\site-packages\pymongo\cursor.py", line 1090, in next
if len(self.__data) or self._refresh():
File "C:\Python27\lib\site-packages\pymongo\cursor.py", line 1012, in _refresh
self.__read_concern))
File "C:\Python27\lib\site-packages\pymongo\cursor.py", line 850, in __send_message
**kwargs)
File "C:\Python27\lib\site-packages\pymongo\mongo_client.py", line 827, in _send_message_with_response
server = topology.select_server(selector)
File "C:\Python27\lib\site-packages\pymongo\topology.py", line 210, in select_server
address))
File "C:\Python27\lib\site-packages\pymongo\topology.py", line 186, in select_servers
self._error_message(selector))
pymongo.errors.ServerSelectionTimeoutError: ds047124.mlab.com:47124: timed out我尝试在“cursor”、“my_cursor”和“collection”上迭代，每一个都提供了服务器超时的回溯错误。如有任何帮助/见解，我们将不胜感激
回答 3
Stack Overflow用户
回答已采纳
发布于 2016-08-24 19:14:53
找到答案后，我将重点放在游标上，而不是将对象从JSON加载到JSON列表中。
最终代码如下(删除URI)
import json
from datetime import date, timedelta
from pymongo import MongoClient
from bson import json_util
#Connect to Mongo Client
client = MongoClient('mongodb://user:pword@ds047124.mlab.com:47124/politicians_from_theage')
db = client.politicians_from_theage #define database used
print db
# Define Collection
collection = db.posts
print collection # print Collection(Database(MongoClient(host=['ds047124.mlab.com:47124']...
cursor = collection.find()
print cursor
# Obtain json
json_docs = []
for doc in cursor:
json_doc = json.dumps(doc, default=json_util.default)
json_docs.append(json_doc)
print json_docs #json result
# List Comprehension version
#json_docs = [json.dumps(doc, default=json_util.default) for doc in cursor]
#To get back from json again as string list
docs = [json.loads(j_doc, object_hook=json_util.object_hook) for j_doc in json_docs]
print docs
print 'kitty terminates program'Stack Overflow用户
发布于 2016-08-24 15:30:25
这可能会对你有所帮助：
# Perform query
cursor = db.posts.find().toAray(function(err, result){
#Iterate the cursor and print the documents.
for document in result:
print(document);
}) //Will give you array of objects.如果它起作用了，请告诉我。
Stack Overflow用户
发布于 2019-05-14 03:18:15
试试这个：
cursor = db.posts.find()
for document in list(cursor):
print(document) 页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/39116919
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