gistfile1.txt

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;
using MongoDB.Bson;
using MongoDB.Bson.IO;
using MongoDB.Bson.Serialization;
using MongoDB.Bson.Serialization.Attributes;
using MongoDB.Bson.Serialization.Conventions;
using MongoDB.Driver;
using MongoDB.Driver.Linq;

namespace TestBugs
{
    internal class Program
    {
        private static void Main(string[] args)
        {
            var client = new MongoClient();
            var db = client.GetDatabase("test");
            db.DropCollection("people");
            var col = db.GetCollection<Person>("people");
            col.InsertOne(new Person
            {
                First = "Jack",
                Last = "McJack",
                Age = 42
            });

            Console.WriteLine("Lambdas");
            var query = col.Find("{}").Project(p => new Person { First = p.First });
            Console.WriteLine(query.ToString());

            foreach (var result in query.ToList())
            {
                Console.WriteLine(result.ToString());
            }


            Console.WriteLine("Projection");
            query = col.Find("{}").Project<Person>(Builders<Person>.Projection.Exclude("Last").Exclude("Age"));
            Console.WriteLine(query.ToString());

            foreach (var result in query.ToList())
            {
                Console.WriteLine(result.ToString());
            }
        }


        public class Person
        {
            public ObjectId Id;
            public string First;
            public string Last;
            public int Age;

            public override string ToString()
            {
                return $"{First} {Last}, {Age}";
            }
        }
    }
}