public static MvcHtmlString MyDropDownListFor <TModel, TProperty>(this HtmlHelper <TModel> htmlHelper, Expression <Func <TModel, TProperty> > expression, IEnumerable <SelectListItem> selectList, string optionLabel, IDictionary <string, object> htmlAttributes)
{
if (expression == null)
{
throw new ArgumentNullException("expression");
}
ModelMetadata metadata = ModelMetadata.FromLambdaExpression(expression, htmlHelper.ViewData);
IDictionary <string, object> validationAttributes = htmlHelper.GetUnobtrusiveValidationAttributes(ExpressionHelper.GetExpressionText(expression), metadata);
if (htmlAttributes == null)
{
htmlAttributes = validationAttributes;
}
else
{
htmlAttributes = htmlAttributes.Concat(validationAttributes).ToDictionary(k => k.Key, v => v.Value);
}
return(SelectExtensions.DropDownListFor(htmlHelper, expression, selectList, optionLabel, htmlAttributes));
}
