how to get the aggregate sum on a set of fields with the same values using mongo

Question

I am trying to find the sum of documents which have the same values on a set of fields using mongo shell, these are sample documents,

{
"id" : "1",
"date" : ISODate("2017-04-29T00:00:00.000Z"),
"amount" : 697,
"name" : "vendor1"
}

{
"id" : "2",
"date" : ISODate("2017-04-29T00:00:00.000Z"),
"amount" : 380
"name" : "vendor2"
}

{
"id" : "2",
"date" : ISODate("2017-04-29T00:00:00.000Z"),
"amount" : 380,
"name" : "vendor2"
}

{
"id" : "3",
"date" : ISODate("2017-04-29T00:00:00.000Z"),
"amount" : 702,
"name" : "vendor3"
}

{
"id" : "3",
"date" : ISODate("2017-04-29T00:00:00.000Z"),
"amount" : 702,
"name" : "vendor3"
}

the query I have tried is,

db.results.aggregate([
{$group:{'_id':{name:'$name', id:'$id', date:'$date', amount:'$amount', 
count:{'$sum':1}}}},
{$match:{'count':{'$gt':1}}}])

but it fetched 0 records. Also I like to know how many such documents have been found, So I am wondering how to solve the issue.

Answer 1

You can use this.

db.results.aggregate([
{ $group:{'_id': {name:'$name', id:'$id', date:'$date', amount:'$amount'}
                 , count: {$sum: 1} } }
])

Result:

{ "_id" : { "name" : "vendor3", "id" : "3", "date" : ISODate("2017-04-29T00:00:00Z"), "amount" : 702 }, "count" : 2 }
{ "_id" : { "name" : "vendor2", "id" : "2", "date" : ISODate("2017-04-29T00:00:00Z"), "amount" : 380 }, "count" : 2 }
{ "_id" : { "name" : "vendor1", "id" : "1", "date" : ISODate("2017-04-29T00:00:00Z"), "amount" : 697 }, "count" : 1 }