DropDownList Result not being Returned - asp.net-mvc-3

Question

I am trying to create an Item that has an ItemType coming from another table. I am unable to get back the actual Type object from the Create page. This is the code I have tried:
Models:
public class ItemType {
public int Id { get; set; }
[Required]
public string Name { get; set; }
public virtual ICollection<Item> Item{ get; set; }
}
public class Item {
public int Id { get; set; }
[Required]
public string Name { get; set; }
public virtual ItemType ItemType { get; set; }
}
In the ItemController, this is my create code:
public ActionResult Create() {
var itemTypeRepo = new ItemTypeRepository(context);
ViewBag.ItemTypes = new SelectList(itemTypeRepo.GetAll(), "ID", "Name");
return View();
}
[HttpPost]
public ActionResult Create(Item item) {
if (ModelState.IsValid) {
context.Items.Add(item);
context.SaveChanges();
return RedirectToAction("Index");
}
return View(item);
}
In my Create.cshtml view I have tried:
<div class="editor-field">
#Html.DropDownList("ItemType", String.Empty)
#Html.ValidationMessageFor(model => model.ItemType)
</div>
This returns no value at all and throws an error "The value 'X' is invalid." Where X is the ID of the ItemType I selected.
And
<div class="editor-field">
#Html.DropDownListFor(x => x.ItemType.Id, (SelectList)ViewBag.ItemType)
#Html.ValidationMessageFor(model => model.ItemType)
</div>
This creates a stub ItemType object with the correct ID but does not insert it into the database since the object is not fully loaded. If I look at ModelState object, I find that there is an error that the Name field is missing from ItemType object.
I also attempted to solve the problem using the second .cshtml code and adding this code:
public ActionResult Create(Item item) {
item.ItemType = context.ItemTypes.Find(item.ItemType.Id);
if (ModelState.IsValid)
This does not change the value of ModelState.IsValid from false even through it should.
What do I need to do to get this to work?

Answer 1

You should add a property ItemTypeId to your Item entity so that it acts as a foreign key.
public class Item
{
public int Id { get; set; }
[Required]
public string Name { get; set; }
public int ItemTypeId { get; set; }
[ForeignKey("ItemTypeId")]
public virtual ItemType ItemType { get; set; }
}
You can then use that property for the dropdownlist:
<div class="editor-field">
#Html.DropDownListFor(x => x.ItemTypeId, (SelectList)ViewBag.ItemType)
#Html.ValidationMessageFor(model => model.ItemType)
</div>