Python MongoDB Aggregate error

Question

This code gives me an error:

TypeError: 'CommandCursor' object has no attribute 'getitem'

However when my friend runs the same code on her computer, she doesn't get an error. I'm using an Intel Pentium CPU on Windows. I have MongoDB running (version 3.4), Python 2.7.13 :: Anaconda 4.3.1 (64-bit).

import json
import pymongo 
from bson import json_util
import re

FROM = "[email protected]"

client = pymongo.MongoClient()
db = client.enron    
mbox = db.mbox

//Get the recipient lists for each message

recipients_per_message = db.mbox.aggregate([
{"$match" : {"From" : re.compile(r".*{0}.*".format(FROM), re.IGNORECASE)}}, 
{"$project" : {"From" : 1, "To" : 1} }, 
{"$group" : {"_id" : "$From", "recipients" : {"$addToSet" : "$To" } } }                    
])['result'][0]['recipients']

//The exact Error was:
TypeError Traceback (most recent call last) 
19 {"$project" : {"From" : 1, "To" : 1} },   
20 {"$group" : {"_id" : "$From", "recipients" : {"$addToSet":"$To" }}}  
---> 21 ])['result'][0]['recipients'] 
TypeError: 'CommandCursor' object has no attribute 'getitem'

Can you provide the exact line of the error? Can you print only the aggregation command without ['result'][0]['recipients']? And which version of mongodb has your friend? — Moi Syme
– Moi Syme, Commented Mar 26, 2017 at 19:14

A. Jesse Jiryu Davis · Accepted Answer · 2017-03-27 02:57:03Z

1

Your friend must be running an old version of both MongoDB and PyMongo. Since PyMongo 3.0, running "aggregate" with PyMongo returns a cursor that you must iterate for results. Try this:

results = list(db.mbox.aggregate([
    {"$match" : {"From" : re.compile(r".*{0}.*".format(FROM), re.IGNORECASE)}}, 
    {"$project" : {"From" : 1, "To" : 1} }, 
    {"$group" : {"_id" : "$From", "recipients" : {"$addToSet" : "$To" } } }                    
]))
recipients_per_message = results['result'][0]['recipients']

answered Mar 27, 2017 at 2:57

A. Jesse Jiryu Davis

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1 Comment

AlyData Over a year ago

@a-jesse-jiryu-davis: I get a TypeError: list indices must be integers, not str

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