MVC3 Razor #Html.DropDownListFor - linq

Question

I could use some help implementing #Html.DropDownListFor. My objective is to filter the list of Products by Category.
This code will display a list box:
#model IEnumerable<Sample.Models.Product>
#{
List<Sample.Models.Category> list = ViewBag.Categories;
var items = new SelectList(list, "CategoryID", "CategoryName");
}
#Html.DropDownList("CategoryID", items)
But I'm having trouble getting #Html.DropDownListFor to work:
#model IEnumerable<Sample.Models.Product>
#{
List<Sample.Models.Category> list = ViewBag.Categories;
var items = new SelectList(list, "CategoryID", "CategoryName");
}
#Html.DropDownListFor(???, #items)
I could use some help constructing the Linq portion of #Html.DropDownListFor.
Here is the model:
public class Product
{
public int ProductID { get; set; }
public string ProductName { get; set; }
public int CategoryID { get; set; }
public string QuantityPerUnit { get; set; }
public Decimal? UnitPrice { get; set; }
public short UnitsInStock { get; set; }
public virtual Category Category { get; set; }
}
public class Category
{
public int CategoryID { get; set; }
public string CategoryName { get; set; }
public virtual ICollection<Product> Products { get; set; }
}

Answer 1

Your view is strongly typed to a collection of products so I suppose that you need a drop down for each product. If this is the case an editor template would work:
#model IEnumerable<Sample.Models.Product>
#Html.EditorForModel()
And then inside ~/Views/Shared/EditorTemplates/Product.cshtml
#model Sample.Models.Product
#{
List<Sample.Models.Category> list = ViewBag.Categories;
var items = new SelectList(list, "CategoryID", "CategoryName");
}
#Html.DropDownListFor(x => x.CategoryID, #items)

Answer 2

My recommendation:
Extend your LINQ data context class with a static function to return a SelectList of all categories, and use Html.DropDownList() to display this list.
Then, add a controller for this same Action that accepts category ID and return the IEnumerable<Product> list that corresponds to that category.

Answer 3

here is another way to do what you want.
In the model I have two entries
public class Product
{
public int CategoryID { get; set; }
public IEnumerable<SelectListItem> Category { get; set; }
}
I then populate the SelectlestItem either from a database or statically.
In the Index.cs controller
product model = new product();
model.Category = <whereever you generated the data>;
return View(model);
In the View
#using (Html.BeginForm("Edit", "Subject", FormMethard.Post, new { id = "genform"}))
{
<div class="vertical-space spaced-field">#Html.DropDownListFor(m => m.CategoryID, model,Category)</div>