SelectedValue which is invalid

[Bart]

What is the best way to handle null values in dropdownlists?
Why is the dropdownlist generating the error
"System.ArgumentOutOfRangeException: 'DropDownList1' has a SelectedValue
which is invalid because it does not exist in the list of items." on null
values?
Should it not be possible to have an empty dropdownlist field?

Thanks
Bart

 

[Phillip Williams]

I would always check before assigning a value to the
DropDownList.SelectedValue like this:

ListItem li = ddl.Items.FindByValue(myValue);
ddl.ClearSelection();
if (li != null) //it means the value is found in the list
{
li.Selected = true; //select the item that was found
}