public class Blog

{

    public int BlogId { get; set; }

    public string Url { get; set; }

    public List<Post> Posts { get; set; }

}

public class Post

{

    public int PostId { get; set; }

    public string Title { get; set; }

    public string Content { get; set; }

    public int BlogId { get; set; }

    public Blog Blog { get; set; }

}

public class MyEFTestContext : DbContext

    {

        public MyEFTestContext (DbContextOptions<MyEFTestContext> options)

            : base(options)

        {

        }

        public DbSet<MyEFTest.Models.Blog> Blog { get; set; }

    }

 modelBuilder.Entity("MyEFTest.Models.Post", b =>

                {

                    b.HasOne("MyEFTest.Models.Blog", "Blog")

                        .WithMany("Posts")

                        .HasForeignKey("BlogId")

                        .OnDelete(DeleteBehavior.Cascade);

                });

public class RssBlog : Blog

{

    public string RssUrl { get; set; }

}

  protected override void Up(MigrationBuilder migrationBuilder)

        {

            migrationBuilder.AddColumn<string>(

                name: "Discriminator",

                table: "Blog",

                nullable: false,

                defaultValue: "");

            migrationBuilder.AddColumn<string>(

                name: "RssUrl",

                table: "Blog",

                nullable: true);

        }