using System;

public class Program

{

    public static void Main()

    {

        /// case 1-----------------------------------------------------------------------------------------------------------------------------------------------------------

         BsonDocument filter = new BsonDocument 

         {

             // match fileter

             {

                    "DeletedDate",BsonNull.Value

              },

             {

                    "_header.LocationId", new BsonDocument("$in", new BsonArray(request.LocationIds))

              }

         };

         var match_stage = new BsonDocument("$match", filter);

        List<BsonDocument> mainPipeline= new List<BsonDocument>();

         mainPipeline.Add(match_stage);

         activitiesCollection = _mongoDatabase.Value.GetCollection<CollectionNameinC#>(collectionName).AggregateAsync<ClaseeName>(mainPipeline).Result.ToList();

        /// case 2------------------------------------------------------------------------------------------------------------------------

        var collection = database.GetCollection<User>(collectionName);

​

var excercice1Aggregate = collection.Aggregate()

    .Match(Builders<User>.Filter.Gte(u => u.Salary, 1500) &

           Builders<User>.Filter.Lte(u => u.Salary, 3000))

    .Group(u => u.Gender,

        ac => new

        {

            gender = ac.Key,

            averageMonthlyExpenses = ac.Average(u => u.MonthlyExpenses),

            total = ac.Sum(u => 1)

        })

    .Project(group => new 

    {

        Gender = group.gender == 0 ? "Male" : "Female",

        AverageMonthlyExpenses = group.averageMonthlyExpenses,

        Total = group.total

    })

    .SortByDescending(group => group.AverageMonthlyExpenses);

var excercice1Result = await excercice1Aggregate.ToListAsync();

    }

}