Question

I’m creating my first MVC helper method, but can’t quite get it. I want to emit the same code as the standard “@Html.TextBoxFor” but with the attribute “title” and its value taken from the model property. This is what I have so far. You can see I’m trying to just use the standard “TextBoxFor” at the end and add my own attribute to it, but that doesn’t seem to be the way to do it.

public static MvcHtmlString TextBoxForWithTitle<TModel, TProperty>(
    this HtmlHelper<TModel> htmlHelper,
    Expression<Func<TModel, TProperty>> expression)
{
    var metaData = ModelMetadata.FromLambdaExpression(expression, htmlHelper.ViewData);
    return htmlHelper.TextBoxFor(expression, new { @title = metaData.DisplayName });
}

Specifically, I get a compile time error:

'System.Web.Mvc.HtmlHelper<TModel>' does not contain a definition for 'TextBoxFor' and no extension method 'TextBoxFor' accepting a first argument of type 'System.Web.Mvc.HtmlHelper<TModel>' could be found (are you missing a using directive or an assembly reference?) D:\DevData\JWilliams\Code\Sandbox\URIntakeMVC2\URIntake\HtmlHelpers.cs  16  31  URIntake

Answer 1

The TextBoxFor is an extension method for the HtmlHelper<TModel> class which lives in the System.Web.Mvc.Html namespace.

And if you want to use an extension method you need to explicitly import its namespace with the using directive. So you are missing the using:

using System.Web.Mvc.Html;

And don’t forget that you are also creating an extension method here (TextBoxForWithTitle), so when you want to use it in your view you also need to using your own TextBoxForWithTitle methods namespace:

@using URIntakeMVC2.URIntake