when use MONGO_URI, error: Another user is already authenticated

[syfun]

I use a cloud mongodb server, version is 3.0.7. But its authMechanism is 'MONGODB-CR', not default 'SCRAM-SHA-1'. So when I used 'MONGODB-CR', occured error 'Another user is already authenticated'. My MONGO_URI:
'mongodb://demo:123456@127.0.0.1:27017/demo?authMechanism=MONGODB-CR'

I read source code, and found the reason,

# flask_pymongo/__init__.py 252-253
if any(auth):
    db.authenticate(username, password)

authenticate not assign mechanism agument, so 'DEFAULT‘ and occured my error.

[lafrech]

Can you try to apply the following changes?

In URI parsing, add this line:

app.config[key('AUTH_MECHANISM')] = parsed['options'].get('authMechanism', 'DEFAULT')

In URI-less config, add this line:

app.config.setdefault(key('AUTH_MECHANISM'), 'DEFAULT')

Then when calling authenticate:

mechanism = app.config[key('AUTH_MECHANISM')]
db.authenticate(username, password, mechanism=mechanism)

This untested patch could help. If it does not work as is, it may be a hint.

[syfun]

@lafrech I used the same solution for this, and thank you for the reply.

[dcrosta]

@syfun I know this is a very old bug and it sounds like you've gotten a workaround for this at this point. But I'm trying to revive this project, and I've just recently merged #88, which I think should fix your issue as well. I'll be releasing 0.5.0 soon. When I do, would you be able to test and confirm here whether that works for you?

[syfun]

@dcrosta Ok for that. This bug is realy old enough. I alreay fixed, but almost forgot that. Sorry for not further communication. I will seriously test after you releasing 0.5.0.

[chattr1n]

@dcrosta in 0.5.0, I get this error. not sure if it's related to this issue above:

File "/home/someuser/.local/lib/python3.5/site-packages/flask_pymongo/init.py", line 97, in init
self.init_app(app, config_prefix)
File "/home/someuser/.local/lib/python3.5/site-packages/flask_pymongo/init.py", line 278, in init_app
auth_mechanism = app.config[key('AUTH_MECHANISM')]
KeyError: 'MONGO_AUTH_MECHANISM'

I went back to 0.4.1 and it works.

[syfun]

@chattr1n @dcrosta I also encounter this error. I found the reason in the code.
When user not define MONGO_URI, AUTH_MECHANISM had no default value.

[dcrosta]

I believe that will be fixed by #93, which I'll be releasing shortly as 0.5.1.

[dcrosta]

0.5.1 is now in PyPI -- please upgrade and let me know if that fixes it. If not, we can dig in deeper here.

[syfun]

@dcrosta That's OK for 0.5.1.

[dcrosta]

Great, thanks for following up!