CODEWITHSUNDEEP
mongodbaggregation-framework
FrankBr
FrankBr

Reputation: 896

List values in MongoDB aggregation pipeline belonging to different documents

I got this result coming from an Aggregation pipeline I did:

{
    "_id" : ISODate("2015-05-14T08:22:09.441Z"),
    "values" : {
        "v1_min" : 15.872267760931187,
        "v1" : 15.909139078185774,
        "v1_max" : 20.6420184124931776
    }
},
{
    "_id" : ISODate("2015-05-13T08:22:09.441Z"),
    "values" : {
        "v1_min" : 2.872263320931187,
        "v1" : 7.909132898185774,
        "v1_max" :44.6498764124931776
    }
},
{...}

do you think it's possible to get a structure like this one

{
        "_id" : [ISODate("2015-05-14T08:22:09.441Z"),ISODate("2015-05-13T08:22:09.441Z")]
        "values" : {
            "v1_min" : [15.872267760931187, 2.872263320931187],
            "v1" : [15.909139078185774, 7.909132898185774]
            "v1_max" : [2.6420184124931776, 44.6498764124931776]
        }
}

adding some others stages to my aggregation pipelines?

If so, how would you do?

I'd not like to handle this via code because I think MongoDB aggregation framework is faster and should do better than me.

Upvotes: 1

Views: 81

Answers (1)

chridam
chridam

Reputation: 103375

Yes, it's quite possible indeed. The following aggregation pipeline will achieve the desired output:

db.collection.aggregate([
    {
        "$group": {
            "_id": null,
            "ids": {
                "$addToSet": "$_id"
            },
            "v1_min": {
                "$push": "$values.v1_min"
            },
            "v1": {
                "$push": "$values.v1"
            },
            "v1_max": {
                "$push": "$values.v1_max"
            }
        }
    },
    {
        "$project": {
            "_id": "$ids",
            "values": {
                "v1_min": "$v1_min",
                "v1": "$v1",
                "v1_max": "$v1_max"
            }
        }
    }
]);

-- EDIT --

Use $push instead of $addToSet as the latter will only add the element if and only if the final array does not contain the element itself. (Thanks to @SylvainLeroux for the positive contributions)

Upvotes: 2

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