How to sort all dropdownLists by name in ASP.net MVC

Create a HtmlHelperExtensions class that has an extension method that does what you want. Something like this:

public static class HtmlHelperExtensions
{
    public static MvcHtmlString SortedDropDownList(this HtmlHelper htmlHelper, string name, IEnumerable<SelectListItem> selectList)
    {
        return htmlHelper.DropDownList(name, selectList.OrderBy(x => x.Text));
    }
}

Whatever namespace you stick the helper in, make sure it's added to configuration\system.web.webPages.razor\pages\namespaces in the web.config found in your \Views folder so that you can use it in your view.

You could create HtmlHelperExtension class as friism sugested, or you could create extension method on SelectList like this:

public static class SortedList
{
        public static void SortList(this SelectList selectList, SortDirection direction)
        {
            //sort content of selectList
        }
}

and then use it like this:

var sel = new SelectList(new List<string> {"john", "mary", "peter"});
sel.SortList(SortDirection.Ascending);

Either way, you are going to change every line of code where you want to sort those lists.