using Microsoft.EntityFrameworkCore;

using System.ComponentModel.DataAnnotations.Schema;

using System.Collections.Generic;

using System.Linq;

using System;

​

namespace EFTest

{

    class Program

    {

        static void Main(string[] args)

        {

            var options = new DbContextOptionsBuilder<BloggingContext>()

                .UseInMemoryDatabase(databaseName: "blarg123")

                .Options;

​

            using (var context = new BloggingContext(options))

            {

                var blog = new Blog { Id = 1, Url = "http://sample.com" };

                var post = new Post { Id = 1, BlogId = 1 };

                context.Add(blog);

                context.Add(post);

                context.SaveChanges();

            }

            using (var context = new BloggingContext(options))

            {

                var post = context.Set<Post>().AsNoTracking().First();

                context.Entry(post).Reference(x => x.Blog).Load();

                Console.WriteLine(post.Blog.Url);

                Console.WriteLine(context.Set<Post>().Local.Count());

                Console.WriteLine(context.Set<Blog>().Local.Count());

            }

        }

    }

​

    public class BloggingContext : DbContext

    {

        public BloggingContext(){ }

​

        public BloggingContext(DbContextOptions<BloggingContext> options)

            : base(options){ }

        protected override void OnModelCreating(ModelBuilder modelBuilder)

        {

            modelBuilder.Entity<Blog>();

            modelBuilder.Entity<Post>()

                .HasOne(x => x.Blog)

                .WithMany()

                .HasForeignKey(x => x.BlogId);

        }

    }

​

    [Table("Blog")]

    public class Blog

    {

        public int Id { get; set; }

        public string Url { get; set; }

    }

​

    [Table("Post")]

    public class Post

    {

        public int Id { get; set; }

        public string Notes { get; set; }

        public Blog Blog { get; set; }

        public int BlogId { get; set; }

    }

​

}