Question

I am using ASP.Net MVC 3, have referenced all the proper DLLs (see included screenshots), but for some reason I get a this compilation error.

Answer 1

This was an odd occurrence. I was able to reproduce your error. I was also able to figure out why it was happening and how to bypass it.

Why It Occurs

There is a namespace collision between System.Web.Mvc.Html and System.Web.WebPages.Html

What the result of the collision was

System.Web.Mvc.Html

This namespace holds a definition for the method

LabelExtensions.Label (HtmlHelper, String, String)

As you will notice, this is the namespace which takes precedent and causes the problem. It has only two overloads. (String) or (String, String). While testing, this was the only option which showed up.

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How to bypass it

What you really wanted was this namespace

System.Web.WebPages.Html

This namespace holds a definition for the method

HtmlHelper.Label (String, String, IDictionary<String, Object>)

You can now see that the availability to add new { @class = "myClass" } is present.

Create your own instance

Get your own HtmlHelper and bypass the LabelExtension like this:

razor

@{
 var h = new System.Web.WebPages.Html.HtmlHelper();
}

asp

<% var h = new System.Web.WebPages.Html.HtmlHelper(); %>

Make sure that this is not nested inside of a razor or <%= block because it will prevent it from being available. It needs to be at the global level of the page.

Use the correct label

Now you may use this:

razor

@h.Label("firstName", "First Name", new { @class = "control-label" })

asp

<%= h.Label("firstName", "First Name", new { @class = "control-label" }) %>