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

Question

我在 python 中使用 for 循环来循环使用 pymongo 的查询结果。代码如下:

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...

我的问题是，如何将变量 myGeolocCountry 插入到现有文档(b)上不存在的字段 geolocCountry ?

我试过了

b['geolocCountry'] = myGeolocCountry

但它根本不起作用，它甚至不会产生错误。

谢谢

Answer 1

您应该像这样执行更新查询:

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