GroupBy using cond to select fields

Question

I'm trying to make a groupBy on mongoDB, using cond to select to appropriate field, however, mongo is giving me: "The field '$cond' must be an accumulator object"

$group{
 "_id" : {"dateId" : "$dateId"},
 "estimated" : { "$sum" : "$estimated_records"},
 $cond: {
   if:  {"activeSelfConsumption" : {"$exists" : true}} , (I'm also not sure if this work)
   then : {"value" : { "$sum" :"$activeSelfConsumption"}}, 
   else : {"value" : { "$sum" :"$active"}} }
}

Possible duplicate of [mongo group and count with condition](https://stackoverflow.com/questions/30169115/mongo-group-and-count-with-condition) — Ashh, Aug 14 '18 at 11:29

score 0 · Accepted Answer · answered Aug 14 '18 at 13:27

0

$cond operator is not required. Use $ifNull instead.

Something like

{"$group":{
 "_id" : {"dateId":"$dateId"},
 "estimated":{"$sum":"$estimated_records"},
 "value":{"$sum":{"$ifNull":['$activeSelfConsumption','$active']}}
}}

answered Aug 14 '18 at 13:27

s7vr

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thanks, yeah, I used exactly that query a few hours after I post the question. – ThePoog Aug 16 '18 at 08:34

GroupBy using cond to select fields

1 Answers1