using System;

using System.Collections.Generic;

using System.Linq;

using MongoDB.Bson.Serialization;

using MongoDB.Driver;

using MongoDB.Driver.Linq;

​

namespace ConsoleApp1

{

    class Order

    {

        public virtual int Id { get; set; }

        public virtual List<OrderItem>  Items { get; set; }

​

        public Order()

        {

            Items = new List<OrderItem>();

        }

    }

    class OrderItem

    {

        public virtual int Id { get; set; }

        public virtual int GoodId { get; set; }

        public virtual int Amount { get; set; }

    }

​

    class Program

    {

        static void Main(string[] args)

        {

            var client = new MongoClient("mongodb://localhost/test");

            var db = client.GetDatabase("test");

            BsonClassMap.RegisterClassMap<Order>(m =>

            {

                m.MapIdProperty(x => x.Id);

                m.MapProperty(x => x.Items);

            });

            BsonClassMap.RegisterClassMap<OrderItem>(m =>

            {

                m.MapIdProperty(x => x.Id);

                m.MapProperty(x => x.GoodId);

                m.MapProperty(x => x.Amount);

            });

            db

                .GetCollection<Order>("orders")

                .InsertOne(

                new Order

                {

                    Id = 1,

                    Items = new List<OrderItem>

                    {

                        new OrderItem{GoodId = 1, Amount = 1},

                        new OrderItem{GoodId = 2, Amount = 10},

                        new OrderItem{GoodId = 3, Amount = 20},

                        new OrderItem{GoodId = 4, Amount = 30},

                        new OrderItem{GoodId = 5, Amount = 40}

                    }

                });

​

            var orders = db

                .GetCollection<Order>("order").AsQueryable()

                .Where(x => x.Items.Select(e => e.GoodId).Contains(2))

                .ToArray();

            /*orders = db

                .GetCollection<Order>("order").AsQueryable()

                .Where(x => x.Items.Select(e => e.GoodId).Any(e => e == 2))

                .ToArray();*/           

        }

    }

}