With The New Razor View Engine, Should My HtmlHelpers Return String Or IHtmlString?

With the Razor View Engine, anytime you output a string directly to the page, it's HTML encoded. e.g.: @'

Hello World

' will actually get output to the page as: &

Solution 1:

In most cases you should return an instance of IHtmlString. That's the pattern followed by the built-in helpers* and it means that the consumer of a helper does not need to worry about under- or over-encoding.

Instead of using the Raw function you should probably just return a new instance of HtmlString.

public static IHtmlString MyCoolHelperMethod(this HtmlHelper helper) {
    return new HtmlString("<p>Hello World</p>");
}

*Note that MVC 3 actually uses MvcHtmlString as the return type of its helpers but this is a holdover from the MVC 2 days. (Complicated story, but in short, IHtmlString was only introduced in .NET 4 and since MVC 2 supported .NET 3.5 the MvcHtmlString type was introduced as an intermediate step). All helpers targetting MVC 3 and higher should return IHtmlString.