Templated Razor Delegates combined with Partial Views

I was with a customer in Germany this week, and just before I left one of the (rather talented I might say) developers asked me about passing markup into an HtmlHelper extension. It turns out this is pretty easy, as covered by Phil Haack under Templated Razor Delegates. However, I particularly like keeping my HTML markup in cshtml files. It’s just easier to maintain. So I combined Phil’s post with the use of a partial view. The nice simple HtmlHelper extension looks like this;

    1:  public static MvcHtmlString Region<TModel>( 
    2:     this HtmlHelper<TModel> html, 
    3:     Func<TModel, object> content) 
    4:  { 
    5:     var result = content(html.ViewData.Model); 
    6:     return html.Partial("_Region", result); 
    7:  } 

This accepts a Func<TModel, object> which is the Templated Razor Delegate. This is quite simply a snippet of Razor syntax that is executed to return markup as “result”.

    1:  @Html.Region(@<text>@Model.WelcomeMessage</text>)

I’ve combined my HtmlHelper extension with a partial view named _Region, stored in the Shared folder;

    1:  <fieldset class="demoregion"> 
    2:      <legend>A Region</legend> 
    3:      <div> 
    4:          @Model 
    5:      </div> 
    6:  </fieldset>

This would be way neater if I could use an @helper under App_Code, but in MVC 3 that feature doesn’t support using HtmlHelper, so you couldn’t use Html.Textbox in the template, for example.

The code is attached – easy huh?