ASP.NET MVC。如何手动将“级联删除”添加到代码优先关系？

public class Category
{
    public int CategoryId { get; set; }
    public string Name { get; set; }
    public virtual ICollection<Product> Products { get; set; }
}

public class Product
{
    public int ProductId { get; set; }
    public string Name { get; set; }
    public int CategoryId { get; set; }
    public virtual Category Category { get; set; }
}

public class ApplicationDbContext : DbContext
{
    public DbSet<Category> Categories { get; set; }
    public DbSet<Product> Products { get; set; }

    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        modelBuilder.Entity<Product>()
            .HasRequired(p => p.Category)
            .WithMany(c => c.Products)
            .HasForeignKey(p => p.CategoryId)
            .WillCascadeOnDelete(true); // 启用级联删除
    }
}

public class CategoryController : Controller
{
    private ApplicationDbContext db = new ApplicationDbContext();

    // GET: Category/Delete/5
    public ActionResult Delete(int? id)
    {
        if (id == null)
        {
            return new HttpStatusCodeResult(HttpStatusCode.BadRequest);
        }
        Category category = db.Categories.Find(id);
        if (category == null)
        {
            return HttpNotFound();
        }
        return View(category);
    }

    // POST: Category/Delete/5
    [HttpPost, ActionName("Delete")]
    [ValidateAntiForgeryToken]
    public ActionResult DeleteConfirmed(int id)
    {
        Category category = db.Categories.Find(id);
        db.Categories.Remove(category);
        db.SaveChanges();
        return RedirectToAction("Index");
    }
}

@model Category

@using (Html.BeginForm("Delete", "Category", new { id = Model.CategoryId }, FormMethod.Post, new { @class = "form-horizontal", role = "form" }))
{
    @Html.AntiForgeryToken()

    <div class="form-group">
        <div class="col-md-offset-2 col-md-10">
            <h4>确定要删除该分类吗？</h4>
            <input type="submit" value="删除" class="btn btn-danger" />
            @Html.ActionLink("返回列表", "Index", null, new { @class = "btn btn-default" })
        </div>
    </div>
}