ASP.NET MVC 2 Preview 2 - Extend LabelExtensions.LabelFor

Question

I'm wondering if anyone has attempted to write an extension helper to the LabelExtensions.LabelFor HtmlHelper in MVC2? This would be useful for me in that my app requires that I always wrap labels in a <td> tag with a class attribute. Rather than have that code repeated in the View I thought I could write a little extension method:

public static MvcHtmlString RenderLabelFor<TModel, TValue> (
    this HtmlHelper html,
    Expression<Func<TModel, TValue>> value,
    object htmlAttributes
) where TModel : class
{
    TagBuilder builder = new TagBuilder("td");
    builder.MergeAttributes(new RouteValueDictionary(attributes)); // to convert an object into an IDictionary
    builder.InnerHtml = LabelExtensions.LabelFor(html, value).ToString();
    return MvcHtmlString.Create(builder.ToString(TagRenderMode.Normal));
}

However I get the error on the LabelFor line:

The type arguments for method 'System.Web.Mvc.Html.LabelExtensions.LabelFor(System.Web.Mvc.HtmlHelper, System.Linq.Expressions.Expression>)' cannot be inferred from the usage. Try specifying the type arguments explicitly.

Can anyone throw me a bone on this one?

Answer 1

try public static MvcHtmlString RenderLabelFor<TModel, TValue> ( this HtmlHelper html, Expression<Func<TModel, TValue>> value, object htmlAttributes) where TModel : class

Answer 2

This may be too late to help you, but you need to use the generic version of HtmlHelper in your method signature, like so:

public static MvcHtmlString RenderLabelFor<TModel, TValue> (
    this HtmlHelper<TModel> html,
    Expression<Func<TModel, TValue>> value,
    object htmlAttributes
)
{
    ...
}