Dropdown onchange加載另一個下拉列表MVC4

Question

我在我的視圖中填充兩個下拉列表（Category和SubCategory）。

我正在通過我的控制器做到這一點，我希望子類別的下拉列表根據類別中選定的項目進行填充。

任何建議如何做到這一點，是否有更好，更有效的方式來填充下拉？

Controller: 

public ActionResult Edit(int id) 
    { 
     EntryViewModel model = (from subcat in dc.SubCategory 
           join en in dc.Entry on subcat.SubCategoryId equals en.SubCategoryId 
           join cat in dc.Category on subcat.CategoryId equals cat.Id 
           where en.Id == id 
           select new EntryViewModel { 
            Id = en.Id, 
            Title = en.Title, 
            Username = en.Username, 
            Password = en.Password, 
            Url = en.Url, 
            Description = en.Description, 
            CategoryId = cat.Id, 
            CategoryName = cat.Name, 
            SubCategoryId = subcat.SubCategoryId, 
            SubCategoryName = subcat.Name 
           }).First(); 

     string selectedCat = (from cat in dc.Category 
          join en in dc.SubCategory on cat.Id equals en.SubCategoryId 
          where cat.Id == en.SubCategoryId 
          select cat.Name).First(); 

     ViewBag.SubjectNameCat = new SelectList(dc.Category, "Id", "Name", selectedCat); 

     string selected = (from cat in dc.SubCategory 
          join en in dc.Entry on cat.SubCategoryId equals en.SubCategoryId 
          where en.Id == id 
          select cat.Name).First(); 

     ViewBag.SubjectName = new SelectList(dc.SubCategory, "SubCategoryId", "Name", selected); 

     return View(model); 
    } 

查看：Shownig只是下拉爲了簡單列表

<div class="editor-label"> 
     Category 
    </div> 
    <div class="editor-field"> 
     @Html.DropDownListFor(model => model.CategoryId, (IEnumerable<SelectListItem>)ViewBag.SubjectNameCat, 
       new { @class = "form-control" }) 
    </div> 

    <div class="editor-label"> 
     SubCategory 
    </div> 
    <div class="editor-field"> 
     @Html.DropDownListFor(model => model.SubCategoryId, (IEnumerable<SelectListItem>)ViewBag.SubjectName, 
       new { @class = "form-control" }) 
    </div> 

Answer 1

@PetarS試試這個真棒插件，最適合我。 https://github.com/rajkaimal/CascadingDropDown