import pymongo causes `ImportError: cannot import name BSON`. how do you fix the import error?
Question:
I’m having trouble getting a simple Hello World app to work using Flask, MongoDB, and Python. The app is bombing when trying to import from the bson
module. All modules were installed successfully via pip
and I’m running in a virtualenv
, so I’m not sure why I’m getting the error: ImportError: cannot import name BSON
Here is my sample app code:
import os
from flask import Flask
from flask import g
from flask import jsonify
from flask import json
from flask import request
from flask import url_for
from flask import redirect
from flask import render_template
from flask import make_response
import pymongo
from pymongo import Connection
from bson import BSON
from bson import json_util
app = Flask(__name__)
@app.route('/')
def hello():
connection = Connection()
# Get your DB
db = connection.my_database
# Get your collection
cars = db.cars
# Create some objects
import datetime
car = {"brand": "Ford",
"model": "Mustang",
"date": datetime.datetime.utcnow()}
# Insert it
cars.insert(car)
json_docs = [json.dumps(doc, default=json_util.default) for doc in cars.find()]
return json_docs
if __name__ == '__main__':
# Bind to PORT if defined, otherwise default to 5000.
port = int(os.environ.get('PORT', 5000))
app.debug = True
app.run(host='0.0.0.0', port=port)
I’m not sure how to go about debugging this or if there’s something I’m missing here.
Edit: results of pip freeze
:
Flask==0.9
Jinja2==2.6
WTForms==1.0.2
Werkzeug==0.8.3
bson==0.3.3
distribute==0.6.28
mongo==0.2.0
pymongo==2.3
pytz==2012g
wsgiref==0.1.2
Edit2: Removed bson and pymongo, reran pip install pymongo
. Complete trace now:
Traceback (most recent call last):
18:21:20 web.1 | File ".../venv/lib/python2.7/site-packages/flask/app.py", line 1701, in __call__
18:21:20 web.1 | return self.wsgi_app(environ, start_response)
18:21:20 web.1 | File ".../venv/lib/python2.7/site-packages/flask/app.py", line 1689, in wsgi_app
18:21:20 web.1 | response = self.make_response(self.handle_exception(e))
18:21:20 web.1 | File ".../venv/lib/python2.7/site-packages/flask/app.py", line 1687, in wsgi_app
18:21:20 web.1 | response = self.full_dispatch_request()
18:21:20 web.1 | File ".../venv/lib/python2.7/site-packages/flask/app.py", line 1361, in full_dispatch_request
18:21:20 web.1 | response = self.make_response(rv)
18:21:20 web.1 | File ".../venv/lib/python2.7/site-packages/flask/app.py", line 1450, in make_response
18:21:20 web.1 | rv = self.response_class.force_type(rv, request.environ)
18:21:20 web.1 | File ".../venv/lib/python2.7/site-packages/werkzeug/wrappers.py", line 711, in force_type
18:21:20 web.1 | response = BaseResponse(*_run_wsgi_app(response, environ))
18:21:20 web.1 | File ".../venv/lib/python2.7/site-packages/werkzeug/test.py", line 818, in run_wsgi_app
18:21:20 web.1 | app_iter = app(environ, start_response)
18:21:20 web.1 | TypeError: 'list' object is not callable
Answers:
Try uninstalling the bson
and pymongo
packages and then reinstalling the pymongo
package. pymongo
installs its own bson
package and I think you’ve overwritten it with the other bson
package installation and that is probably what is causing your import error.
FYI:
- when you pip install pymongo it also installs bson but it does not ever print a message saying that it is install bson to your virtualenv site-packages
- also pymongo does not list bson as a dep
- also pip -v list does not show that bson is installed
- those bullet points IMO have some code smell (at least print a message stating you are installing bson)
You are returning a list in hello()
. You need to return a string or a Response object, see Flask docs. E.g. convert the list to a string before returning:
return 'n'.join(json_docs)
I met the same problem.
I think the reason is I install pymongo
and then install bson
.
Then I uninstall bson. Then I got this problem.
pip freeze pymongo
it requires Nothing.
So maybe it has its own bson package.
What I solve this problem:
pip uninstall pymongo
pip uninstall bson
and then reinstall pymongo
pip install pymongo
I’m having trouble getting a simple Hello World app to work using Flask, MongoDB, and Python. The app is bombing when trying to import from the bson
module. All modules were installed successfully via pip
and I’m running in a virtualenv
, so I’m not sure why I’m getting the error: ImportError: cannot import name BSON
Here is my sample app code:
import os
from flask import Flask
from flask import g
from flask import jsonify
from flask import json
from flask import request
from flask import url_for
from flask import redirect
from flask import render_template
from flask import make_response
import pymongo
from pymongo import Connection
from bson import BSON
from bson import json_util
app = Flask(__name__)
@app.route('/')
def hello():
connection = Connection()
# Get your DB
db = connection.my_database
# Get your collection
cars = db.cars
# Create some objects
import datetime
car = {"brand": "Ford",
"model": "Mustang",
"date": datetime.datetime.utcnow()}
# Insert it
cars.insert(car)
json_docs = [json.dumps(doc, default=json_util.default) for doc in cars.find()]
return json_docs
if __name__ == '__main__':
# Bind to PORT if defined, otherwise default to 5000.
port = int(os.environ.get('PORT', 5000))
app.debug = True
app.run(host='0.0.0.0', port=port)
I’m not sure how to go about debugging this or if there’s something I’m missing here.
Edit: results of pip freeze
:
Flask==0.9
Jinja2==2.6
WTForms==1.0.2
Werkzeug==0.8.3
bson==0.3.3
distribute==0.6.28
mongo==0.2.0
pymongo==2.3
pytz==2012g
wsgiref==0.1.2
Edit2: Removed bson and pymongo, reran pip install pymongo
. Complete trace now:
Traceback (most recent call last):
18:21:20 web.1 | File ".../venv/lib/python2.7/site-packages/flask/app.py", line 1701, in __call__
18:21:20 web.1 | return self.wsgi_app(environ, start_response)
18:21:20 web.1 | File ".../venv/lib/python2.7/site-packages/flask/app.py", line 1689, in wsgi_app
18:21:20 web.1 | response = self.make_response(self.handle_exception(e))
18:21:20 web.1 | File ".../venv/lib/python2.7/site-packages/flask/app.py", line 1687, in wsgi_app
18:21:20 web.1 | response = self.full_dispatch_request()
18:21:20 web.1 | File ".../venv/lib/python2.7/site-packages/flask/app.py", line 1361, in full_dispatch_request
18:21:20 web.1 | response = self.make_response(rv)
18:21:20 web.1 | File ".../venv/lib/python2.7/site-packages/flask/app.py", line 1450, in make_response
18:21:20 web.1 | rv = self.response_class.force_type(rv, request.environ)
18:21:20 web.1 | File ".../venv/lib/python2.7/site-packages/werkzeug/wrappers.py", line 711, in force_type
18:21:20 web.1 | response = BaseResponse(*_run_wsgi_app(response, environ))
18:21:20 web.1 | File ".../venv/lib/python2.7/site-packages/werkzeug/test.py", line 818, in run_wsgi_app
18:21:20 web.1 | app_iter = app(environ, start_response)
18:21:20 web.1 | TypeError: 'list' object is not callable
Try uninstalling the bson
and pymongo
packages and then reinstalling the pymongo
package. pymongo
installs its own bson
package and I think you’ve overwritten it with the other bson
package installation and that is probably what is causing your import error.
FYI:
- when you pip install pymongo it also installs bson but it does not ever print a message saying that it is install bson to your virtualenv site-packages
- also pymongo does not list bson as a dep
- also pip -v list does not show that bson is installed
- those bullet points IMO have some code smell (at least print a message stating you are installing bson)
You are returning a list in hello()
. You need to return a string or a Response object, see Flask docs. E.g. convert the list to a string before returning:
return 'n'.join(json_docs)
I met the same problem.
I think the reason is I install pymongo
and then install bson
.
Then I uninstall bson. Then I got this problem.
pip freeze pymongo
it requires Nothing.
So maybe it has its own bson package.
What I solve this problem:
pip uninstall pymongo
pip uninstall bson
and then reinstall pymongo
pip install pymongo