MongoDB 2.1 Aggregate Framework Sum of Array Elements matching a name

Question

This is a question about the best way to add up a series of data in an array where I have to match another element. I\'m trying to use the 2.2 Aggregation framework and it\'

Answer 1

You can use the aggregation framework to get sales and profit and any other value you may be storing in your key/value pair representation.

For your example data:

var pipeline = [
    {
        "$unwind" : "$finance"
    },
    {
        "$group" : {
            "_id" : "$finance.k",
            "numberOf" : {
                "$sum" : 1
            },
            "total" : {
                "$sum" : "$finance.v.v"
            }
        }
    }
]

R = db.tb.aggregate( pipeline );
printjson(R);
{
        "result" : [
            {
                "_id" : "profit",
                "numberOf" : 2,
                "total" : 246246
            },
            {
                "_id" : "sales",
                "numberOf" : 2,
                "total" : 468000
            }
        ],
        "ok" : 1
}

If you have additional k/v pairs then you can add a match which only passes through k values in ["sales","profit"].