convert pymongo cursor to json

Question

I know this is a fairly common problem. I'm writing a small Flask app and I'm trying to feed some queries back to the view. I've connected to my local MongoDB setup, and made a successful query - but I can't generate a json object with it.

The most common solution I've seen is to import json_util from pymongo i.e.

import json
from pymongo import json_util

results = connection.get_collection('papayas_papaya')
results = results.find({
    'identifier': '1',
})
serialized_results = [json.dumps(result, default=json_util.default, separators=(',', ':')) for result in results]

I've installed pymongo into my Flask virtualenv using pip i.e :

pip install pymongo

When running the above code I keep getting the following error:

ImportError: cannot import name json_util

I can see this line in the pymongo-2.3-py2.6.egg-info/installed-files.txt ../bson/json_util.py

Anyone got any tips that can help me figure out what I'm doing wrong?

UPDATE: Having noodled about with this a little further - I've managed to get this working thus:

import pymongo
from bson.json_util import dumps

connection = pymongo.Connection("localhost", 27017)
db = connection.mydocs

def get():
    cursor = db.foo.find({"name" : "bar"})
    return dumps(cursor)

One of the problems I had was trying to pip install bson independently - pymongo brings bson with it and importing bson separately caused problems.

Thanks @Cagex for pointing me in the right direction

Never "pip install bson", that's someone else's obsolete module. Only "pip install pymongo" to get the official pymongo, bson, and gridfs modules. — A. Jesse Jiryu Davis, May 30 '14 at 13:30

Brian Cajes · Accepted Answer · 2021-10-06T04:11:10.780

16

It looks like you want to import from bson not pymongo. I believe json_util was moved to that module recently. https://pymongo.readthedocs.io/en/stable/api/bson/json_util.html

edited Oct 06 '21 at 04:11

answered Nov 06 '12 at 01:53

Brian Cajes

3,274
3
21
22

url not work 202111005 – Lonyui Oct 05 '21 at 03:46

score 6 · Answer 2 · edited Jul 16 '23 at 21:17

6

I've seen quite a few posts on this issue but they didn't resolve the issue for me. What worked for me was using dumps(), then loads():

import pymongo
from bson.json_util import dumps
from bson.json_util import loads
    
connection = pymongo.Connection("localhost", 27017)
db = connection.mydocs
    
def get():
    cursor = db.foo.find({"name" : "bar"})
    return loads(dumps(cursor))

edited Jul 16 '23 at 21:17

mrazizi

319
2
15

answered Jan 27 '20 at 20:44

This prints only the headings and not the values – Navi Jun 23 '20 at 13:47

score 2 · Answer 3 · answered Mar 17 '20 at 06:20

you can use list() to convert pymongo cursor to json object.

import pymongo
from bson.json_util import dumps
from bson.json_util import loads

connection = pymongo.Connection("localhost", 27017)
db = connection.mydocs

def get():
   cursor = list(db.foo.find({"name" : "bar"}))
   return loads(dumps(cursor))

Giorgos Myrianthous · Answer 4 · 2023-01-06T11:26:47.797

You first need define your own JSONEncoder:

import json
from datetime import datetime
from typing import Any

from bson import ObjectId


class MongoJSONEncoder(json.JSONEncoder):
    def default(self, o: Any) -> Any:
        if isinstance(o, ObjectId):
            return str(o)
        if isinstance(o, datetime):
            return str(o)
        return json.JSONEncoder.default(self, o)

And then use it to encode the Mongo cursor:

data_json = MongoJSONEncoder().encode(list(cursor))

that you can then load as a Python object with json.loads():

data_obj = json.loads(data_json)

convert pymongo cursor to json

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