You can create a Form Helper class to create a custom drop down list, and create a custom 'selectListItem' class that has an extra property 'itemsHtmlAttributes' of type IDictionary - see below. You may need to play around with the 'id' or 'name' attributes to get the default model binding working. Below is a bit messy, I would suggest using TagBuilder to build the 'select' and 'option' tags:
public class SelectListItemCustom : SelectListItem
{
public IDictionary<string, object> itemsHtmlAttributes { get; set; }
}
public static class FormHelper
{
public static MvcHtmlString DropDownListForCustom(this HtmlHelper htmlHelper, string id, List<SelectListItemCustom> selectListItems)
{
var selectListHtml = "";
foreach (var item in selectListItems)
{
var attributes = new List<string>();
foreach (KeyValuePair<string, string> dictItem in item.itemsHtmlAttributes)
{
attributes.Add(string.Format("{0}='{1}'", dictItem.Key, dictItem.Value));
}
// do this or some better way of tag building
selectListHtml += string.Format(
"<option value='{0}' {1} {2}>{3}</option>", item.Value,item.Selected ? "selected" : string.Empty,string.Join(" ", attributes.ToArray()),item.Text);
}
// do this or some better way of tag building
var html = string.Format("<select id='{0}' name='{0}'>{1}</select>", id, selectListHtml);
return new MvcHtmlString(html);
}
}
VIEW:
@{
var item = new SelectListItemCustom { Selected = true, Value = "123", Text = "Australia", itemsHtmlAttributes = new Dictionary<string, object> { { "countrycode", "au" } } };
var items = new List<SelectListItemCustom> { item };
Html.Raw(Html.DropDownListForCustom("insertIdHere", items))
}