Mini How To Make a drop down via Html Convention

attribute.cs

//annotate your view model property with this attribute

[AttributeUsage(AttributeTargets.Property | AttributeTargets.Field)]
public class GbstListValueAttribute : Attribute
{
	private readonly string _listName;

	public GbstListValueAttribute(string listName)
	{
		_listName = listName;
	}

	public virtual string GetListName(Type type)
	{
		return _listName;
	}
}

elementbuilder.cs

public class GbstListValueDropdownBuilder : ElementBuilder
{
	protected override bool matches(AccessorDef def)
	{
		var hasAttribute = def.Accessor.HasAttribute<GbstListValueAttribute>();
			
		return hasAttribute;
	}

	public override HtmlTag Build(ElementRequest request)
	{
		return new SelectTag(tag =>
		                     {
		                     	var defaultValue = buildOptions(request, tag);

		                     	tag.SelectByValue(defaultValue);
		                     });
	}

	private static string buildOptions(ElementRequest request, SelectTag tag)
	{
		var defaultValue = request.Value<string>();
		var listElements = GetListElementsOrderedByRank(request);
		
		foreach (var e in listElements)
		{
			if (e.IsDefault && defaultValue.IsEmpty()) defaultValue = e.Title;
			tag.Option(e.Title, e.Title);
		}
		
		return defaultValue;
	}

	private static IEnumerable<ListElement> GetListElementsOrderedByRank(ElementRequest request)
	{
		var att = request.Accessor.GetAttribute<GbstListValueAttribute>();
		var listName = att.GetListName(request.Accessor.OwnerType);

		var listCache = request.Get<IListCache>();
		var gbstList = listCache.GetGbstList(listName);

		return gbstList.ActiveElements
			.OrderBy(e => e.Rank)
			.Select(element => new ListElement
				                {
				                Title = element.Title,
				                IsDefault = element.Equals(gbstList.DefaultElement)
				                });
	}

	private class ListElement
	{
		public string Title { get; set; }
		public bool IsDefault { get; set; }
	}
}