Question

我正在使用Flask建立一个网站，我在其中使用带有MongoEngine ORM的MongoDB。为了重新开始，我现在升级了我的ubuntu 14.04开发机器上的所有apt和pip包。不幸的是，这破坏了我与MongoDB的联系：

Traceback (most recent call last):
  File "./run.py", line 4, in <module>
    from app import app, socketio
  File "/home/kr65/beta/app/__init__.py", line 21, in <module>
    mongoDb = MongoEngine(app)
  File "/usr/local/lib/python2.7/dist-packages/flask_mongoengine/__init__.py", line 33, in __init__
    self.init_app(app)
  File "/usr/local/lib/python2.7/dist-packages/flask_mongoengine/__init__.py", line 66, in init_app
    self.connection = mongoengine.connect(**conn_settings)
  File "/usr/local/lib/python2.7/dist-packages/mongoengine/connection.py", line 164, in connect
    return get_connection(alias)
  File "/usr/local/lib/python2.7/dist-packages/mongoengine/connection.py", line 126, in get_connection
    raise ConnectionError("Cannot connect to database %s :\n%s" % (alias, e))
mongoengine.connection.ConnectionError: Cannot connect to database default :
False is not a read preference.

我检查了MongoDB是否已启动：

$ sudo service mongodb status
mongodb start/running, process 781

如果我可以进入交互式命令行：

$ mongo
MongoDB shell version: 2.4.9
connecting to: test
Welcome to the MongoDB shell.
For interactive help, type "help".
For more comprehensive documentation, see
    http://docs.mongodb.org/
Questions? Try the support group
    http://groups.google.com/group/mongodb-user
Server has startup warnings:
Tue Apr 14 09:14:10.267 [initandlisten]
Tue Apr 14 09:14:10.267 [initandlisten] ** WARNING: You are running in OpenVZ. This is known to be broken!!!
Tue Apr 14 09:14:10.267 [initandlisten]
>

我没有改变任何代码或密码或类似的东西。我重新启动并重新启动了mongoDB，但没有任何作用。我的设置是这样的：

MONGODB_SETTINGS = {
    'db': 'mydatabasename'
}

我实例化了这样的连接（之前有效）：

app = Flask(__name__)
app.config.from_object('config')
mongoDb = MongoEngine(app)

由于我没有真正改变任何事情，我有点不确定在哪里寻找解决方案。有没有人有任何提示我怎么解决这个问题？

[编辑] 有了@lapinkoira的提示我的MongoDB现在正确启动，但我现在在查询时得到以下错误。任何想法如何解决这个？

File "/home/kr65/beta/app/views/webviews.py", line 476, in getDoc
    userDoc = UserDocument.objects(id=docId).first()
  File "/usr/local/lib/python2.7/dist-packages/mongoengine/queryset/base.py", line 309, in first
    result = queryset[0]
  File "/usr/local/lib/python2.7/dist-packages/mongoengine/queryset/base.py", line 160, in __getitem__
    return queryset._document._from_son(queryset._cursor[key],
  File "/usr/local/lib/python2.7/dist-packages/mongoengine/queryset/base.py", line 1410, in _cursor
    **self._cursor_args)
  File "/usr/local/lib/python2.7/dist-packages/pymongo/collection.py", line 924, in find
    return Cursor(self, *args, **kwargs)
TypeError: __init__() got an unexpected keyword argument 'snapshot'

Answer 1

看起来你已经安装了pymongo 3.0。

Mongoengine还不兼容它。

您可以尝试通过

解决此问题

pip uninstall pymongo
pip install pymongo==2.8

Answer 2

看起来您的默认read_preference值为False，请尝试此操作，添加到您的导入：

from pymongo import read_preferences

这是你的mongo配置字典：

'read_preference': read_preferences.ReadPreference.PRIMARY

Answer 3

如果使用monogengine＆gt; = 3和python＆gt; = 3和Ubuntu
写 /usr/local/lib/python3.5/dist-packages/mongoengine /

中的from pymongo import read_preferences

并在sudo gedit connection.py的同一目录中打开终端并在 def register_connection 中更换 'read_preference': read_preferences.ReadPreference.PRIMARY在函数的参数中它就像魅力

升级后无法连接到MongoDB？

3 个答案: