Question

I want to write a HtmlHelper extension method similar to HiddenFor. The difference is that I want to control what goes into the value attribute as well as tack on an extra attribute. I figured I could just look at the source code for MVC, being as how its open source and all. But, unless I am blind, it appears that the strongly typed helper methods like HiddenFor, TextBoxFor, etc, are not included in the source code.

The method signature uses Expression> expression.

Given the expression how can I get the same value of the name attribute that HiddenFor would?

Answer 1

But, unless I am blind, it appears that the strongly typed helper
methods like HiddenFor, TextBoxFor, etc, are not included in the
source code

Everything is included in the source code, just download it and look at InputExtensions.cs.

So to get the name:

public static MvcHtmlString FooBarFor<TModel, TProperty>(
    this HtmlHelper<TModel> htmlHelper, 
    Expression<Func<TModel, TProperty>> expression
) 
{
    var name = ExpressionHelper.GetExpressionText(expression);
    var fullHtmlFieldName = htmlHelper
        .ViewContext
        .ViewData
        .TemplateInfo
        .GetFullHtmlFieldName(name);

    // do something with the name
    ...
}

ModelMetadata metadata = ModelMetadata.FromLambdaExpression(expression, htmlHelper.ViewData)