filter by month number using aggregation pipeline

Program.cs

using MongoDB.Driver;
using MongoDB.Entities;
using MongoDB.Entities.Core;
using System;

namespace StackOverFlow
{
    public class Item : Entity
    {
        public DateTime DateOfCreation { get; set; }
    }

    public static class Program
    {
        private static void Main()
        {
            new DB("test", "localhost");

            new[] {
                new Item { DateOfCreation = new DateTime(2020,3,1,0,0,0,DateTimeKind.Utc) },
                new Item { DateOfCreation = new DateTime(2020,3,2,0,0,0,DateTimeKind.Utc) },
                new Item { DateOfCreation = new DateTime(2020,3,3,0,0,0,DateTimeKind.Utc) },
            }.Save();

            //https://dev.to/djnitehawk/overcoming-the-limitations-of-mongodb-c-driver-1110
            var pipeline = new Template<Item>(@"
            [{
                $match: {
                    $expr: {
                        $eq: [
                            { $month: '$<DateOfCreation>' },
                            <month_number>
                        ]
                    }
                }
            }]")

            .Path(i => i.DateOfCreation)
            .Tag("month_number", "3");

            var result = DB.Aggregate(pipeline).ToList();
        }
    }
}