[RESOLVED] MVC 3 DropDownListFor problem

[gavio]

Hello.

I'm using VS2010, MVC 3, Razor and Entity Framework 4.

I want to have a drop down list with list of all countries from the Countries table. And in my model, I have just a single country id (Guid).

So, in my Model, I have:

public Guid? CountryID
{ get; set; }

In my Controller, I have:

ViewBag.Countries = from e in new MyEntities().Countries select e;

And in my View, I have:

@Html.DropDownListFor(m => m.CountryID, new SelectList(ViewBag.Countries, "CountryID", "Name"), "")

If I choose something or not, i get the "Value cannot be null", on the View line of the code (@Html.DropDown...). What am I doing wrong?

Also, cause I'm totally new to MVC and Entity Framework, is there a better way to achieve this? I'm Googling this for few hours now with no results...

EDIT: I have just seen I've posted in the wrong forum section, so please, redirect this. Sorry.

[gep13]

EDIT: I have just seen I've posted in the wrong forum section, so please, redirect this. Sorry.

No problem

Moved to the MVC Forums.

Gary

[gavio]

Ok. Got it working with a little bit of a different approach.

Model:

public UserRegistrationModel()
{
	this.InitializeCountries();
}

private void InitializeCountries()
{
	FarmerEntities fe = new FarmerEntities();
	var query = from c in new FarmerEntities().Countries select new { ID = c.ID_Country, Name = c.ISO_Code };
	var countries = query.ToSelectList(c => c.ID.ToString(), c => c.Name);

	this.Countries = countries;
}

public Guid? { get; set; }

public IEnumerable<SelectListItem> Countries
{ get; set; }

Controller:

UserRegistrationModel model = new UserRegistrationModel();

return View(model);

View:

@Html.DropDownListFor(m => m.Country, Model.Countries, "")

Also, you need to implement this extension:

public static class EnumerableExtensions
{
	public static IEnumerable<SelectListItem> ToSelectList<TItem, TValue>(this IEnumerable<TItem> items, Func<TItem, TValue> valueSelector, Func<TItem, string> nameSelector)
	{
		return items.ToSelectList(valueSelector, nameSelector, x => false);
	}

	public static IEnumerable<SelectListItem> ToSelectList<TItem, TValue>(this IEnumerable<TItem> items, Func<TItem, TValue> valueSelector, Func<TItem, string> nameSelector, IEnumerable<TValue> selectedItems)
	{
		return items.ToSelectList(valueSelector, nameSelector, x => selectedItems != null && selectedItems.Contains(valueSelector(x)));
	}

	public static IEnumerable<SelectListItem> ToSelectList<TItem, TValue>(this IEnumerable<TItem> items, Func<TItem, TValue> valueSelector, Func<TItem, string> nameSelector, Func<TItem, bool> selectedValueSelector)
	{
		foreach (var item in items)
		{
			var value = valueSelector(item);

			yield return new SelectListItem
			{
				Text = nameSelector(item),
				Value = value.ToString(),
				Selected = selectedValueSelector(item)
			};
		}
	}
}