Question

I’m a brand new user here – but I’ve been searching for a couple of hours now to solve following problem:

I’ve got 2 Entities – Category and Item.
Each Item should belong to a Category – therefore I would like to have a DropDownList which shows all existing Categories when Creating a new Item.
So far my code shows the DropDownList with all the Categories, but when I select a Category and Submit the form (POST) the value for Category is always null.
This naturally causes ModelState.IsValid to be false, because Category isn’t nullable.
How can I get the User-Selected-Value into my Create(POST) method?

I've got a Controller with following Methods to Create a new Item:

// GET Method
public ActionResult Create()
{
    ViewBag.Category = new SelectList(db.CategorySet, "Id", "CategoryName");
    return View();
}
[HttpPost]
public ActionResult Create(Item item)
{
    if (ModelState.IsValid)
    {
      db.ItemSet.Add(item);
      db.SaveChanges();
      return RedirectToAction("Index");
    }

return View(item);
}

And this is the DropDownList in my View (Create.cshtml):
<div class="editor-field">
@Html.DropDownList("Category", (IEnumerable<SelectListItem>) ViewBag.Categories, "--Select Category--")
</div>

Answer 1

Finally I ended up with a custom view model – that way I got it working…

For those of you who don’t know what a custom view model is:
You create a new class which contains all the values you need to create your new object, in my example a class which contains a SelectList (property) of available Categories, an integer value (property) for SelectedCategoryId and the Item (property) you want to create.
In your cshtml file you add this class as @model ….CustomCreateItemModel and use it in your DropDownList