printing data other than $group in mongo using aggregation frame work

[shankar gandhi]

I am trying to print data apart from fields used in $group but didn't found any way.

for e.g my query is 

     db.test.aggregation({"$project": "status":1,"cost":1 },{"$group":{_id: "name","cost"}})

it will print only "cost" not "status". Let me know hot to do it in mongo

[Rhys Campbell]

Provide a few sample documents.

[Amar Singh]

By default $group gives only the the grouped field value. You can use $first, $last, $push for getting other fields.

One example could be like this

db.test.aggregation({"$project": "status":1,"cost":1 },{"$group":{_id: "name","cost"},"status":{"$first":"$status"}})

You can use other operators as well.

Amar Singh

On Mon, Apr 25, 2016 at 12:48 PM, Rhys Campbell <rhys.jame...@gmail.com> wrote:

Provide a few sample documents.

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[Asya Kamsky]

Amar is right, but I would add to that that you should remove the
$project stage.

Your $project stage is not doing anything useful so it's going to slow
down performance of the pipeline. Aggregation already examines the
pipeline to see which fields it needs to output the final result so
using $project to "prune down" the fields is counter-productive.

Asya

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