Collect values on grouped field

Question

With given data

{
    "type": "INGESTION",
    "message": "Lorem"
}

{
    "type": "INGESTION",
    "message": "Ipsum"
}

{
    "type": "DISCHARGE",
    "message": "dolor"
}

{
    "type": "DISCHARGE",
    "message": "sit"
}

I want to group by type and collecting all possible values of message into one single field.

The expected output should be something along the lines of

[{
    "type": "INGESTION",
    "messages": ["Lorem", "Ipsum"]
},
{
    "type": "DISCHARGE",
    "messages": ["dolor", "sit"]
}]

I have tried several aggregation queries, none of which have led to a result that I could be satisfied with.

score 1 · Accepted Answer · answered May 28 '19 at 11:51

1

There is an example on the doc which describes your same situation.

db.your_collection.aggregate([
    {
        $group: {
            "_id": "$type",
            "messages": { $push: "$message" }
        }
    }
]);

answered May 28 '19 at 11:51

Marco Luzzara

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Alternatively use `$addToSet` instead of `$push` if you do want unique entries in that array – manuelgu May 28 '19 at 12:10

Collect values on grouped field

1 Answers1