如何根据MVC Dot网中选定的子类别显示类别，子类别和获取产品？

Question

我是MVC dot net的新手。对于电子商务应用程序，我需要填充类别和子类别。通过单击子类别，所有产品都应基于所选子类别显示。但我不知道如何解决这个问题。

这是我的模特

public class Category
{
    public int CategoryId { get; set; }
    public string CategoryName { get; set; }
}
public class SubCategory
{
    public int SubCategoryId { get; set; }
    public string SubCategoryName { get; set; }
    public int CategoryId { get; set; }
}

数据库中的子类别表：

SubcategoryId    SubCategoryName     CategoryId
  1                 NIKE                 1
  2                 ADIDAS               1
  3                 FENDI                2
  4                 GUCCI                2

控制器：

CategoryManager manager=new CategoryManager();
    public ActionResult Index()
    {
        ViewBag.Categories = manager.GetCategories();
        ViewBag.SubCategories = manager.GetSubCategories();
        return View();
    }

查看控制器：

@using EcommerceApp.Models;
@{
List<Category> allCategories = null;
  allCategories=  ViewBag.Categories;
//...Code for Subcategory....//
}
 @if (allCategories!= null)
       {
           foreach (var catagories in allCategories)
            {

                <div class="panel panel-default">
                    <div class="panel-heading">
                        <h4 class="panel-title">
                            <a data-toggle="collapse" data-parent="#accordian" href="#@catagories.CategoryId

                               ">
                                <span class="badge pull-right"><i class="fa fa-plus"></i></span>
                                @catagories.CategoryName
                            </a>
                        </h4>
                    </div>
                    <div id="@catagories.CategoryId" class="panel-collapse collapse">
                        <div class="panel-body">
                            <ul>   
                                @*<li><a href="#">....Code For Subcategory...</a></li>*@
                            </ul>
                        </div>
                    </div>
                </div>

            }
       }

SUbCategory的网关：

 public List<SubCategory> GetSubCategories()
    {
        List<SubCategory> subCategoryList = new List<SubCategory>();
        SqlConnection connection = new SqlConnection(ConnectionString);
        string query = "SELECT * FROM SubCategory";
        SqlCommand command = new SqlCommand(query, connection);
        connection.Open();
        SqlDataReader reader = command.ExecuteReader();
        while (reader.Read())
        {
            SubCategory subCategory = new SubCategory();
            subCategory.CategoryId = (int)reader["CategoryId"];
            subCategory.SubCategoryName = reader["SubCategoryName"].ToString();
            subCategory.SubCategoryId = (int) reader["SubCategoryId"];
            subCategoryList.Add(subCategory);
        }
        return subCategoryList;

    }

此代码填充了类别，但我不知道如何填充相应的子类别并根据子类别ID获取产品。在Controller，Model和View中需要写什么或改变什么？