Pymongo/bson: Convert python.cursor.Cursor object to serializable/JSON object

Question

New to MongoDb and Python (webapp2). So, I was fetching some data from a mongodb database. But I was unable to use json.dumps on the returned data. Here's my code:

exchangedata = db.Stock_Master.find({"Country": "PHILIPPINES"}, {"_id" : 0})        
self.response.write(json.dumps(exchangedata))

This throws an error:

TypeError: pymongo.cursor.Cursor object at 0x7fcd51230290 is not JSON serializable

The type of exchangedata is pymongo.cursor.Cursor. How can I convert it into a json object?

Related: http://stackoverflow.com/questions/13241878/convert-pymongo-cursor-to-json. — alecxe, May 19 '15 at 18:27
Convert the cursor to a list of objects: `self.response.write(json.dumps(list(exchangedata)))` — Kyle Pittman, May 19 '15 at 18:28
Mongo returns a `cursor` object instead of an actual `list` of data. You will need to convert that to a `list` first as Kyle mentioned. — Martin Konecny, May 19 '15 at 18:41
Not working with the list wrapper. It sends across an empty data object. — Tarun Dugar, May 20 '15 at 06:22

score 35 · Accepted Answer · answered May 22 '15 at 15:13

35

Use dumps from bson.json_util:

>>> c = pymongo.MongoClient()
>>> c.test.test.count()
5
>>> from bson.json_util import dumps
>>> dumps(c.test.test.find())
'[{"_id": {"$oid": "555cb3a7fa5bd85b81d5a624"}}, {"_id": {"$oid": "555cb3a7fa5bd85b81d5a625"}}, {"_id": {"$oid": "555cb3a7fa5bd85b81d5a626"}}, {"_id": {"$oid": "555cb3a7fa5bd85b81d5a627"}}, {"_id": {"$oid": "555cb3a7fa5bd85b81d5a628"}}]'

answered May 22 '15 at 15:13

Bernie Hackett

8,749
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2

this solution is good only for very small dataset as it dumps all of the objects fetched by the cursor to a single string. With bigger data it doesn't help and you can as well iterate over all of the results and just save them. – hashark Nov 22 '18 at 10:53
1

bson package is really bad for large data. Use the bsonjs package instead. In most cases it should suffice for you to convert the ObjectId() alone. – XChikuX Nov 28 '18 at 17:35
dumps(c.test.test.find(), indent=4) is better. – Evan Knox Thomas Jan 11 '21 at 14:48

score 2 · Answer 2 · answered Oct 06 '18 at 14:15

2

Simple Solution

 // Use dumps from bson.json_util:
from bson.json_util import dumps

@app.route("/")
def home_page():

    booking = dumps(mongo.db.bookings.find())
    print booking
    return  booking

answered Oct 06 '18 at 14:15

Shashwat Gupta

5,071
41
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score 0 · Answer 3 · edited Nov 15 '20 at 08:56

0

Yes, of course you can use the dumps() in bson.json_util package. But, the dumps() will give you quoted results. To get clear json result you can use the following code.

clean_json = re.compile('ISODate\(("[^"]+")\)').sub('\\1', 
        dumps(my_db._my_collection.find(query), 
                 json_options=CANONICAL_JSON_OPTIONS))
json_obj = json.loads(clean_json)

edited Nov 15 '20 at 08:56

Siddhartha

340
2
9

answered Mar 27 '20 at 01:26

Shirantha Madusanka

1,461
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16

Pymongo/bson: Convert python.cursor.Cursor object to serializable/JSON object

3 Answers3

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