实体框架7迁移未创建表

我正在使用Entity Framework 7进行我的第一个项目，并且正在连接到一个SQL Server，该SQL Server已经创建了数据库，但其中还没有表。我已经创建了DbContext并创建了一个类，然后在上下文中设置了DbSet<>。我运行了启用迁移的命令并创建了第一个迁移，然后用rand命令更新数据库。一切看起来都很好，没有出现任何错误，但当我查看数据库时，只创建了EFMigraitonsHistory表。当我看到为初始迁移创建的类时，它基本上是空白的。我做错了什么？

我正在运行的命令：

dnvm install latest -r coreclr
dnx ef migrations add MyFirstMigration
dnx ef database update

上下文：

namespace JobSight.DAL
{
    public class JobSightDBContext : DbContext
    {
        public DbSet<NavigationMenu> NavigationMenu { get; set; }
    }
}

表类别：

namespace JobSight.DAL
{
    public class NavigationMenu
    {
        [Required, DatabaseGenerated(DatabaseGeneratedOption.Identity)]
        public Int16 ID { get; set; }
        public string ControllerName { get; set; }
        public string ActionName { get; set; }
        public string ExternalURL { get; set; }
        public string Title { get; set; }
        public Int16? ParentID { get; set; }
        public virtual NavigationMenu Parent { get; set; }
    }
}

Startup.cs:

    public void ConfigureServices(IServiceCollection services)
    {
        services.AddMvc();
        services.AddEntityFramework()
                .AddSqlServer()
                .AddDbContext<JobSightDBContext>(options =>
                {
                    options.UseSqlServer(Configuration["Data:JobSightDatabase:ConnectionString"]);
                });
    }

用于初始迁移的类（由EF自动生成）：

namespace JobSight.WebUI.Migrations
{
    public partial class Initial : Migration
    {
        protected override void Up(MigrationBuilder migrationBuilder)
        {
        }
        protected override void Down(MigrationBuilder migrationBuilder)
        {
        }
    }
}

编辑：在做了Poke建议的事情之后，这是我新的自动生成的迁移。但是，该表仍然没有在数据库级别创建。

namespace JobSight.WebUI.Migrations
{
    public partial class MyFirstMigration : Migration
    {
        protected override void Up(MigrationBuilder migrationBuilder)
        {
            migrationBuilder.CreateTable(
                name: "NavigationMenu",
                columns: table => new
                {
                    ID = table.Column<short>(nullable: false)
                        .Annotation("SqlServer:ValueGenerationStrategy", SqlServerValueGenerationStrategy.IdentityColumn),
                    ActionName = table.Column<string>(nullable: true),
                    ControllerName = table.Column<string>(nullable: true),
                    ExternalURL = table.Column<string>(nullable: true),
                    ParentID = table.Column<short>(nullable: true),
                    Title = table.Column<string>(nullable: true)
                },
                constraints: table =>
                {
                    table.PrimaryKey("PK_NavigationMenu", x => x.ID);
                    table.ForeignKey(
                        name: "FK_NavigationMenu_NavigationMenu_ParentID",
                        column: x => x.ParentID,
                        principalTable: "NavigationMenu",
                        principalColumn: "ID",
                        onDelete: ReferentialAction.Restrict);
                });
        }
        protected override void Down(MigrationBuilder migrationBuilder)
        {
            migrationBuilder.DropTable("NavigationMenu");
        }
    }
}

protected override void OnModelCreating(ModelBuilder modelBuilder)
{
    base.OnModelCreating(modelBuilder);
    modelBuilder.Entity<NavigationMenu>();
}

dnx ef migrations add Example -p JobSight.DAL

dnx ef database update