Python - Aggregation of MongoDB with "match" condition

Question

I'm trying to get a count of a value in my collection. Here's a sample:

{
    "_id" : ObjectId("583e86987f22def116c35055"),
    "createdby" : "DEO007",
    "valid" : 1
}

In each document, some "valid" are 0 and some are 1. In my case, I only want the total count of documents grouped by "createdby" which has "valid" : 1.

I tried this in MongoDB and it worked without any error :

db.tme_data.aggregate([{ $match: { valid: 1 } },{"$group": {"_id":"$createdby" , "count":{"$sum":1}}}])

But I'm not able to implement the same in my python code. This is what I tried :

collection.aggregate([{"$match":{"$valid":"1"}}, {"$group": {"_id":"$createdby" , "count":{"$sum":1}}}])

It gave me a blank collection.

PS:

1) I'm using pymongo

2) This is working properly in my python code :

collection.aggregate([{"$group": {"_id":"$createdby" , "count":{"$sum":1}}}])

Possible duplicate of MongoDB aggregate/group/sum query translated to pymongo query — user1211
– user1211, Commented Nov 30, 2016 at 9:44
@user3632894 I even tried using pipe as explained in the solution to the question mentioned by you. But either the explanation is too concise or I am making some mistake. Either way, a more detailed solution would be helpful. — Anubhav
– Anubhav, Commented Nov 30, 2016 at 9:53

Ravi Makwana · Accepted Answer · 2022-09-29 10:30:26Z

1

Why do you have {"$valid":"1"} in your python code. Its a field to be matched.

It should be {"valid":"1"}

edited Sep 29, 2022 at 10:30

Ravi Makwana

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answered Nov 30, 2016 at 9:56

user1211

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3 Comments

Anubhav Over a year ago

I knew it was some small error. Thanks for pointing out. I made this mistake while copying this thing from my php code.

Anubhav Over a year ago

Can you explain why do I need to use $ with createdby in db.tme_data.aggregate([{ $match: { valid: 1 } },{"$group": {"_id":"$createdby" , "count":{"$sum":1}}}]?

user1211 Over a year ago

$ is basically a literal. It provides access to a field. For better understanding refer: docs.mongodb.com/v3.2/reference/operator/aggregation/literal/…

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