How can I call DisplayFor from inside of a custom extension

Question

I am trying to write some HtmlHelper extension to clean up my views. I have a need to use Html.DisplayFor() to render my model. I write the following extension

public static MvcHtmlString MakeTableBodyTd(this HtmlHelper html, ModelMetadata metaData)
{
    var td = new TagBuilder("td");

    if (metaData != null)
    {
        var cssClassName = metaData.AdditionalValues.GetValueOrDefault("TextAlignment", "left");

        td.AddCssClass(cssClassName);

        var t = html.DisplayFor(x => metaData.Model, metaData.DataTypeName, new { Metadata = metaData }).ToHtmlString();

        td.InnerHtml = t;
    }

    return new MvcHtmlString(td.ToString());
}

However, this extension is giving me this error

'HtmlHelper' does not contain a definition for 'DisplayFor' and no extension method 'DisplayFor(...)' accepting a first argument of type 'HtmlHelper' could be found (are you missing a using directive or an assembly reference?

I am able to use @Html.DisplayFor(...) in my views with no issues, but unable to use the in the extensions class.

I have added a reference to the following libraries

using System.Web.Mvc;
using System.Web.Mvc.Html;

But still giving me the error.

The html has only the following methods available html.Display(), html.DisplayForModel(), html.DisplayName(), html.DisplayNameForModel() and html.DisplayText()

How can I use the html.DisplayFor(...) method inside my extension?

Answer 1

You need to change the the signature of the method to include <TModel> in order to use the ***For() methods.

public static MvcHtmlString MakeTableBodyTd<TModel>(this HtmlHelper<TModel> html, ModelMetadata metaData)
{
    ....
}