I'm trying to extend DropDownListFor in such a way that to preserve the original functionality, but add the functionality that if the selected value that is given is Null, to a new value to the SelectListItem list such as 'Select an item'.
How would you do that?
EDIT: (I wasn't clear at the beginning)
If we look at the default DropDownListFor behavior, the extension gets a list of SelectItems and the 'selected' value. In my app, sometimes the 'selected' value is Null, thus no option is selected from the SelectItems list. I would like to change the default behavior in such a way, that if my 'selected' value is Null, then the DropDown will add automatically a new value such as 'Select an Item' and select it as the 'selected'.
Hope it's better now :)
Thanks
OK, Did it! For future reference here is the solution:
I've create an extension method for the DropDownListFor:
public static MvcHtmlString KeywordDropDownListFor<TModel, TValue>(this HtmlHelper<TModel> helper, Expression<Func<TModel, TValue>> expression,
IEnumerable<SelectListItem> selectList, object htmlAttributes)
{
Func<TModel, TValue> method = expression.Compile();
string value = method(helper.ViewData.Model) as string;
if (String.IsNullOrEmpty(value))
{
List<SelectListItem> newItems = new List<SelectListItem>();
newItems.Add(new SelectListItem
{
Selected = true,
Text = Strings.ChooseAKeyword,
Value = String.Empty
});
foreach (SelectListItem item in selectList)
{
newItems.Add(item);
}
return helper.DropDownListFor(expression, newItems, htmlAttributes);
}
return helper.DropDownListFor(expression, selectList, htmlAttributes);
}
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