如果我在外壳中运行：

mongo ds0219xx.mlab.com:219xx/dbname -u user -p pass

它可以正常工作，并允许我连接到数据库并提取信息。但是，如果我在python应用程序（Flask）中，并运行以下命令：

import pymongo

client = pymongo.MongoClient("mongodb://user:pass@ds0219xx.mlab.com:219xx/dbname")

db = client["dbname"]

db.users.insert_one({
  "user1": "hello"
})

它给了我一个：

pymongo.errors.OperationFailure: Authentication failed.

我很确定它在进入insert_one（）调用之前会失败，但是我不确定。

谢谢！

编辑：通过请求，这是完整的回调：

Traceback (most recent call last):
File "run.py", line 1, in <module>
from app import app
File "/Users/Derek/Documents/programming/shenalum/app/__init__.py", line 6, in <module>
from app import views
File "/Users/Derek/Documents/programming/shenalum/app/views.py", line 4, in <module>
from data import get_posts, get_user_info
File "/Users/Derek/Documents/programming/shenalum/app/data.py", line 9, in <module>
"user1": "hello"
File "/usr/local/lib/python2.7/site-packages/pymongo/collection.py", line 622, in insert_one
with self._socket_for_writes() as sock_info:
File "/usr/local/Cellar/python/2.7.11/Frameworks/Python.framework/Versions/2.7/lib/python2.7/contextlib.py", line 17, in __enter__
return self.gen.next()
File "/usr/local/lib/python2.7/site-packages/pymongo/mongo_client.py", line 718, in _get_socket
with server.get_socket(self.__all_credentials) as sock_info:
File "/usr/local/Cellar/python/2.7.11/Frameworks/Python.framework/Versions/2.7/lib/python2.7/contextlib.py", line 17, in __enter__
return self.gen.next()
File "/usr/local/lib/python2.7/site-packages/pymongo/server.py", line 152, in get_socket
with self.pool.get_socket(all_credentials, checkout) as sock_info:
File "/usr/local/Cellar/python/2.7.11/Frameworks/Python.framework/Versions/2.7/lib/python2.7/contextlib.py", line 17, in __enter__
return self.gen.next()
File "/usr/local/lib/python2.7/site-packages/pymongo/pool.py", line 541, in get_socket
sock_info.check_auth(all_credentials)
File "/usr/local/lib/python2.7/site-packages/pymongo/pool.py", line 306, in check_auth
auth.authenticate(credentials, self)
File "/usr/local/lib/python2.7/site-packages/pymongo/auth.py", line 436, in authenticate
auth_func(credentials, sock_info)
File "/usr/local/lib/python2.7/site-packages/pymongo/auth.py", line 416, in _authenticate_default
return _authenticate_scram_sha1(credentials, sock_info)
File "/usr/local/lib/python2.7/site-packages/pymongo/auth.py", line 188, in _authenticate_scram_sha1
res = sock_info.command(source, cmd)
File "/usr/local/lib/python2.7/site-packages/pymongo/pool.py", line 213, in command
read_concern)
File "/usr/local/lib/python2.7/site-packages/pymongo/network.py", line 99, in command
helpers._check_command_response(response_doc, None, allowable_errors)
File "/usr/local/lib/python2.7/site-packages/pymongo/helpers.py", line 196, in _check_command_response
raise OperationFailure(msg % errmsg, code, response)

pymongo.errors.OperationFailure：身份验证失败。