mongodb - how to find and then aggregate

Question

I have collection that contains documents with below schema. I want to filter/find all documents that contain the gender female and aggregate the sum of brainscore. I tried the below statement and it shows a invalid pipeline error.

db['!all'].aggregate({ $and: [ {'GENDER' :  'F'} , {'DOB' : { $gte : 19400801, $lte : 20131231 }} ]  }, { $group : { _id : "$GENDER", totalscore : { $sum : "$BRAINSCORE" } } } ) 

Schema:

{     "_id" : ObjectId("53f63fc8f2b643f6ebb8a1a9"),     "DOB" : 19690112,     "GENDER" : "F",     "BRAINSCORE" : 65 }, {     "_id" : ObjectId("53f63fc8f2b643f6ebb8a1a2"),     "DOB" : 19950116,     "GENDER" : "F",     "BRAINSCORE" : 44 }, {     "_id" : ObjectId("53f63fc8f2b643f6ebb8a902"),     "DOB" : 19430216,     "GENDER" : "M",     "BRAINSCORE" : 71 } 

Answer 1

You have to use $match:

db['!all'].aggregate([   {$match:     {'GENDER': 'F',      'DOB':       { $gte: 19400801,         $lte: 20131231 } } },   {$group:      {_id: "$GENDER",      totalscore:{ $sum: "$BRAINSCORE"}}} ]) 

Outputs:

{ "_id" : "F", "totalscore" : 109 } 

Answer 2

Sample working query :

db.getCollection('NOTIF_EVENT_RESULT').aggregate([ {$match:     {'userId': {'$in' : ['user-900', 'user-1546']},     'criteria.operator': 'greater than', 'criteria.thresold' : '90', 'category' : 'capacity'} }, {"$group" :  {_id : {userId:"$userId"}, "count" : { "$sum" : 1} } } ])