Aggregation query returning array of all objects for mongodb

Question

I'm using mongo for the first time. I'm trying to aggregate some documents in a collection using the query below. Instead the query returns an object with a key "result" that contains an array of all the documents that fit with $match.

Below is the query.

db.events_2015_04_10.aggregate([
                {$group:{
                     _id: "$uid",
                     count: {$sum: 1},
                    },
                    $match : {promo:"bc40100abc8d4eb6a0c68f81f4a756c7", evt:"login"}
                }
            ]
        );

Below is a sample document in the collection:

{
    "_id" : ObjectId("552712c3f92ea17426000ace"),
    "product" : "Mobile Safari",
    "venue_id" : NumberLong(71540),
    "uid" : "dd542fea6b4443469ff7bf1f56472eac",
    "ag" : 0,
    "promo" : "bc40100abc8d4eb6a0c68f81f4a756c7",
    "promo_f" : NumberLong(1),
    "brand" : NumberLong(17),
    "venue" : "ovation_2480",
    "lt" : 0,
    "ts" : ISODate("2015-04-10T00:01:07.734Z"),
    "evt" : "login",
    "mac" : "00:00:00:00:00:00",
    "__ns__" : "wifipromo",
    "pvdr" : NumberLong(42),
    "os" : "iPhone",
    "cmpgn" : "fc6de34aef8b4f57af0b8fda98d8c530",
    "ip" : "192.119.43.250",
    "lng" : 0,
    "product_ver" : "8"
}

I'm trying to get it all grouped by uid's with the total sum of each group... What is the correct way to achieve this?

chridam · Accepted Answer · 2015-04-11 07:17:12Z

1

Try the following aggregation framework which has the $match pipeline stage first and then the $group pipeline later:

db.events_2015_04_10.aggregate([
    {
        $match: {
            promo: "bc40100abc8d4eb6a0c68f81f4a756c7", 
            evt: "login"
        }
    },
    {
        $group: {
            _id: "$uid",
            count: {
                $sum: 1
            }
        }        
    }
])

edited Apr 11, 2015 at 7:17

answered Apr 10, 2015 at 18:49

chridam

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