Question

I created an HtmlHelper method called DisplayListBoxFor that will need display a textual representation of the selected items in a MultiSelectList as an unordered list (UL/LI) in the browser. I have specific reasons to keep the signature between the standard ListBoxFor and my custom DisplayListBoxFor exactly the same, which means that my method needs to accept a lambda expression. I have the following code in my helpers class that is modeled off of the Html.ListBoxFor method:

public static MvcHtmlString DisplayListBoxFor<TModel, TProperty>(this HtmlHelper<TModel> htmlHelper, Expression<Func<TModel, TProperty>> expression, IEnumerable<SelectListItem> selectList)
{
  TagBuilder tag = new TagBuilder("ul");
  foreach (var value in ((MultiSelectList)selectList).SelectedValues)
  {
    TagBuilder itemTag = new TagBuilder("li");
    itemTag.SetInnerText(value.ToString());
    tag.InnerHtml += itemTag.ToString();
  }
  return new MvcHtmlString(tag.ToString());
}

I can then call my custom method like so:

@Html.DisplayListBoxFor(x => Model.MySelectedValues, Model.MyAvailableValues)

The types I used are as follows:

Model.MySelectedValues = List<Object> 
Model.MyAvailableValues = MultiSelectList

This works just fine, with the exception that the output only lists the ID value and not the name of the selected value because that is all that is stored in the MultiSelectList.SelectedValues property upon creation. I am trying to find a way in my foreach loop to match up the selected value to the value name, but since everything within the method is an anyonymous type, I can’t cast it to any non-concrete values or even use an Indexer to find the id and name properties. How would I be able to get these values from the anonymous types passed to this method?

Answer 1

I figured out a solution to this, but I posted in a separate post where I “dumbed down” the question. See MVC Method to output unordered list from the ListBoxFor method