SelectLists and null values

Question

User-1328661193 posted

Most times I don't want a preselected item.

It's too bad that

SelectList(System.Collections.IEnumerable items, string dataValueField, string dataTextField, object selectedValue)

doesn't take a null for selectedValue and automatically appends a <option value="" /> to the <select>.

Answer 1

User-1660457439 posted

This works perfectly fine on my machine:

            object[] somearray = new object[] {
                new { Foo = "Foo1", Bar = "Bar1" },
                new { Foo = "Foo2", Bar = "Bar2" }
            };
            SelectList somelist = new SelectList(somearray, "Foo", "Bar", null);
            ViewData["somelist"] = somelist;

Then in the view:

<%= Html.DropDownList("somelist") %>

This produces:

<select name="somelist" id="somelist">
<option value="Foo1">Bar1</option>
<option value="Foo2">Bar2</option>
</select>

(By the way, yes, you really do want a default selected item according to the W3C.  We're considering automatically preselecting the first item if no item in the dropdownlist is selected.)

Answer 2

User-1772813213 posted

There should be someway to specify if the list value is being saved to a nullable type and if so a blank option should be placed at the start of the list.

For example, say I have an object:

public class Person {
	public int AddressCountryID { get; set; }
	public int? BirthCountryID { get; set; }
}

I don't want to have to have 2 different Country lists on my viewdata just to add a null value to one of them.

We don't want to encourage people having "Please select an option..."; that is not right, but the situation above is a common and viable one.