ASP.NET

@Html.DropDownList("CategoryList", "Select Category")

@Html.DropDownListFor(model => model.Category.ID, ViewBag.CategoryList, "Select A Category")

@Html.DropDownListFor(model => model.Category.ID, (SelectList)ViewBag.listProducts, "Select A Category")

public class MerchandiseViewModel
{
    public int CategoryList { get; set; }
}

public class MerchandiseViewModel
{
    public Category Category { get; set; }
}

public ActionResult Test()
{
    List<Category> cats = new List<Category>();
    cats.Add(new Category { ID = 1, Name = "Category 1" });
    cats.Add(new Category { ID = 2, Name = "Category 2" });
    cats.Add(new Category { ID = 3, Name = "Category 3" });

    ViewBag.CategoryList = cats;

    return View();
}

[HttpPost]
public ActionResult Test(MerchandiseViewModel mvm)
{
    List<Category> cats = new List<Category>();
    cats.Add(new Category { ID = 1, Name = "Category 1" });
    cats.Add(new Category { ID = 2, Name = "Category 2" });
    cats.Add(new Category { ID = 3, Name = "Category 3" });

    ViewBag.CategoryList = cats;

    return View(mvm);
}

@using (Html.BeginForm())
{
    <p>
        @Html.DropDownListFor(m => m.Category.ID, new SelectList(ViewBag.CategoryList, "ID", "Name"), "Select a category")
    </p>
    <p>
        <input type="submit" value="Submit"/>
    </p>
}

public class MerchandiseServiceClient
{
       private string BaseURL = "http://localhost:14000/MerchandiseService.svc/";
       public Merchandise FindMerchandiseByID(string id)
       {
           try
           {
               var webClient = new WebClient();
               string url = string.Format(BaseURL + "FindMerchandiseByID/{0}", id);
               var javascriptSerializer = new JavaScriptSerializer();
               return javascriptserializer.Deserialize<Merchandise>(jsn);
           }
           catch
           {
               return null;
           }
       }

       public List<Category> FindAllCategories()
       {
           try
           {
               var webClient = new WebClient();
               var jsn = webClient.DownloadString(BaseURL + "FindAllCategories");
               var javascriptSerializer = new JavaScriptSerializer();
               return javascriptSerializer.Deserialize<List<Category>>(jsn);
           }
           catch
           {
               return null;
           }
       }
       .
       .
       .
       .
}

[HttpGet]
public ActionResult Edit(string id)
{
  MerchandiseServiceClient msc = new MerchandiseServiceClient();  
  ViewBag.categoryList = msc.FindAllCategories();
          
  MerchandiseViewModel mvm = new MerchandiseViewModel();
  mvm.Merchandise = msc.FindMerchandiseByID(id);
            
  return View("Edit", mvm);   
}

<tr>
 <td>@Html.LabelFor(model=>model.Category.ID, "Category")</td>
 <td> @Html.DropDownListFor(model => model.Category.ID, (SelectList)ViewBag.categoryList, "Select A Category")</td>  
</tr>

@Html.DropDownListFor(model => model.Category.ID, (SelectList)ViewBag.categoryList, "Select A Category")</

@Html.DropDownListFor(m => m.Category.ID, new SelectList(ViewBag.categoryList, "ID", "Name"), "Select a category")

Dictionary<string, string> Categories { get; set; }

public class model_items
{
  int ID { get; set; }
  string SKU { get; set; }
  int CategoryID { get; set; }

  Dictionary<string, string> select_Categories { get; set; }
}

@Html.DropDownFor(m => m.CategoryID, new SelectList(@Model.selectCategory), "-- Select Category --")

model_items model = new model_items();
model = load_items(1);
model.selectCategories = load_Categories();

@Html.DropDownListFor(model => model.Category.ID, ViewBag.CategoryList, "Select Category")