Stack Overflow Question 54352309

StackOverflowQuestion54352309.cs

using Microsoft.EntityFrameworkCore;
using Microsoft.EntityFrameworkCore.Metadata.Builders;
using System;
using System.Collections.Generic;

namespace HelloConsoleCore
{
    class Program
    {
        static void Main(string[] args)
        {
            var optionsBuilder = new DbContextOptionsBuilder<MyDbContext>()
            .UseInMemoryDatabase("testdb");

            using (var context = new MyDbContext(optionsBuilder.Options))
            {
                var gameMtmCollection = new Game_Mtm_Collection { };

                var game = new Game { Id = Guid.NewGuid(), Name = "Test Game" };

                var anotherGameMtmCollection = new Game_Mtm_Collection();

                var collection = new Collection { Id = Guid.NewGuid(), Name = "Test Collection", Game_Mtm_Collections = new List<Game_Mtm_Collection> { gameMtmCollection, anotherGameMtmCollection } };

                gameMtmCollection.CollectionId = collection.Id;
                gameMtmCollection.Collection = collection;
                gameMtmCollection.GameId = game.Id;
                gameMtmCollection.Game = game;
                context.Add(collection);
                context.SaveChanges();
            }

            Console.WriteLine("Press any key to exit");
            Console.ReadKey();
        }
    }

    public class MyDbContext : DbContext
    {
        public MyDbContext(DbContextOptions<MyDbContext> options) : base(options) { }

        protected override void OnModelCreating(ModelBuilder builder)
        {
            base.OnModelCreating(builder);

            EntityTypeBuilder<Game> game = builder.Entity<Game>();

            EntityTypeBuilder<Collection> collection = builder.Entity<Collection>();

            EntityTypeBuilder<Game_Mtm_Collection> game_Mtm_Collection = builder.Entity<Game_Mtm_Collection>();
            game_Mtm_Collection.HasKey(_ => new { _.GameId, _.CollectionId });
            game_Mtm_Collection.HasOne(_ => _.Game)
              .WithMany(_ => _.Game_Mtm_Collections)
              .HasForeignKey(_ => _.GameId);

            game_Mtm_Collection.HasOne(_ => _.Collection)
              .WithMany(_ => _.Game_Mtm_Collections)
              .HasForeignKey(_ => _.CollectionId);
        }
    }

    public class Game
    {
        public Guid Id { get; set; }
        public string Name { get; set; }
        public List<Game_Mtm_Collection> Game_Mtm_Collections { get; set; }
    }

    public class Collection
    {
        public Guid Id { get; set; }
        public string Name { get; set; }
        public List<Game_Mtm_Collection> Game_Mtm_Collections { get; set; }
    }

    public class Game_Mtm_Collection
    {
        public Guid GameId { get; set; }
        public Game Game { get; set; }
        public Guid CollectionId { get; set; }
        public Collection Collection { get; set; }
    }
}