python + pymongo: how to insert a new field on an existing document in mongo from a for loop

Question

I'm using a for loop in python to loop over the result of a query with pymongo. Here is the code:

from pymongo import MongoClient connection = MongoClient() db = connection.Test  myDocs = db.Docs.find( { "geolocCountry" : { "$exists" : False } } )  for b in myDrives:     my_lat = b['TheGpsLog'][0]['latitude']     my_long = b['TheGpsLog'][0]['longitude']      myGeolocCountry = DoReverseGeocode(lat_start,long_start)      #    Here I perform a reverse geocoding, it does not matter for this example.      #    The important thing is: it returns a string, like 'US', 'UK', etc... 

The question I have is, how can I insert the variable myGeolocCountry into the non existing field geolocCountry on the existing document (b)?

I tried with

b['geolocCountry'] = myGeolocCountry 

but it didn't work at all, it does not even produce an error.

Thanks

Answer 1

You should execute an update query like this:

db.Doc.update({"_id": b["_id"]}, {"$set": {"geolocCountry": myGeolocCountry}}) 

Answer 2

For pymongo > 3

db.Doc.update_one({"_id": b["_id"]}, {"$set": {"geolocCountry": myGeolocCountry}}) 

In case of multiple updates:

db.Doc.update_many({"geolocCountry": {"$exists": False}}, {"$set": {"geolocCountry": myGeolocCountry}}) 

For pymongo < 3

above/previous answers are correct

db.Doc.update({"_id": b["_id"]}, {"$set": {"geolocCountry": myGeolocCountry}}) 

In case of multiple updates:

db.Doc.update({"geolocCountry": {"$exists": False}}, {"$set": {"geolocCountry": myGeolocCountry}})