Question

I am creating a custom helper method for a Drop Down List with the following signature:

public static MvcHtmlString MyCustomDropDownListFor<TModel, TProperty>(this HtmlHelper<TModel> html, Expression<Func<TModel, TProperty>> expression, IEnumerable<SelectListItem> selectList, string optionLabel, object htmlAttributes)

Within the method, I can do the following to get the selected value:

var Value = ((SelectList)selectList).SelectedValue);

In my helper method, I need to find out what the selected text is as well, and not just the value. How will I get that?

Answer 1

If you already have selected value you can just iterate through the IEnumerable trying to find the selected SelectListItem:

        SelectListItem[] items = selectList.ToArray();
        SelectListItem selectedItem = items.FirstOrDefault(i => i.Value == valueAsString) 
            ?? items[0];
        string selectedText = selectedItem.Text;

From my opinion, casting to SelectList is not the best option to find selected value, this casting could throw InvalidCastException when real type of selectList variable is other than SelectList.

In most cases your model contains a value that should be selected in the drop down list. You can get this value using ModelMetadata classes as follows:

        //Get value from model or from ModelState
        object modelValue = ModelMetadata
             .FromLambdaExpression(expression, html.ViewData).Model;

        SelectListItem[] items = selectList.ToArray();

        string selectedValue = modelValue == null ? null : modelValue.ToString();

        SelectListItem selectedItem = items.FirstOrDefault(i => i.Value == selectedValue) 
            ?? items.FirstOrDefault();

        string selectedText = selectedItem == null ? null : selectedItem.Text;

        //Rest code goes here