CODEWITHSUNDEEP
c#mongodbmongodb-csharp-2.0
Vladyslav Furdak
Vladyslav Furdak

Reputation: 1835

MongoDb Count after aggregation C# 2.0 driver

I have the following aggregation pipline 

var count = dbCollection.
Aggregate(new AggregateOptions { AllowDiskUse = true }).Match(query).
Group(groupby).
ToListAsync().Result.Count();

And this gets the following result: 

{
    "result" : [ 
        {
            "_id" : {
                "ProfileId" : ObjectId("55f6c727965bb016c81971ba")
            }
        }, 
        {
            "_id" : {
                "ProfileId" : ObjectId("55f6c727965bb016c81971bb")
            }
        }
    ],
    "ok" : 1
}

But it seems it will make count operation on client, but how to perform it in MongoDb ? I have MongoDb 2.0 C# driver & MongoDb v. 3.0.2

Upvotes: 9

Views: 2775

Answers (1)

Alex Krupka
Alex Krupka

Reputation: 730

Add a constant field to your group function and then group again on the constant field (so that all the results are grouped into a single group) with a aggregate sum of 1. The first (and only) result will have the sum.

Ex. 

var count = dbCollection.
Aggregate(new AggregateOptions { AllowDiskUse = true }).Match(query).
Group(groupby).Group(<id>:{ConstantField},Total:{$sum:1})
ToListAsync().Result.First().GetValue("Total").

Upvotes: 6

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