README.md

Sample Usage

Example from unrender.js:

 <tbody>
   @helper rows(YourItemType item)
   {
     <tr ng-repeat-start="item in Model.Items">
       <td ng-bind="item.Name" data-unrender="unbind">
         @item.Name
       </td>
       <td ng-bind="item.NumberInStock" data-unrender="unbind">
         @item.NumberInStock
       </td>
       <td ng-bind="item.PricePerEach" data-unrender="unbind">
         @item.PricePerEach
       </td>
     </tr>
     <tr ng-repeat-end data-unrender="unloop">
       <td colspan="3" ng-bind="item.Description" data-unrender="unbind">
         @item.Description
       </td>
     </tr>
   }
   @helper empty()
   {
     <tr ng-if="!Model.Items.length">
       <td colspan="3">
         Sorry, no items at this time.
       </td>
     </tr>
   }
   @* 
     The 'if' block has been placed first so that
     the 'unloop' transformation doesn't wipe out
     the <script> from the 'if' block.
   *@
   @Html.If(!Model.Items.Any(), empty)
   @Html.Foreach(Model.Items, rows)
 </tbody>

Caveats

The implementation is kind of quick and naive. When using Foreach, if your collection is null or empty, it will create a dummy object for whatever type you passed in, so make sure all of the expressions in your template are fail-safe with a dummy object (having automated tests for your web app wouldn't hurt, either.) Take similar precautions when referencing your model within an if/else/switch/case block simulated with If.

IsomorphicRazorExtensions.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web.Mvc;
using System.Web.WebPages;

public static class IsomorphicRazorExtensions
{
    public static HelperResult Foreach<T>(this HtmlHelper helper, IEnumerable<T> items, Func<T, HelperResult> template)
        where T : class, new()
    {
        if (items == null || !items.Any())
        {
            return new HelperResult(writer =>
            {
                var wrapper = new TagBuilder("script");
                wrapper.Attributes.Add("type", "text/html");
                wrapper.Attributes.Add("data-unrender", "unpack");

                writer.Write(wrapper.ToString(TagRenderMode.StartTag));
                template(new T()).WriteTo(writer);
                writer.Write(wrapper.ToString(TagRenderMode.EndTag));
            });
        }
        else
        {
            return new HelperResult(writer =>
            {
                foreach (var item in items)
                {
                    template(item).WriteTo(writer);
                }
            });
        }
    }

    public static HelperResult If(this HtmlHelper helper, bool condition, Func<HelperResult> template)
    {
        if (condition)
        {
            return new HelperResult(writer =>
            {
                template().WriteTo(writer);
            });
        }
        else
        {
            return new HelperResult(writer =>
            {
                var wrapper = new TagBuilder("script");
                wrapper.Attributes.Add("type", "text/html");
                wrapper.Attributes.Add("data-unrender", "unpack");

                writer.Write(wrapper.ToString(TagRenderMode.StartTag));
                template().WriteTo(writer);
                writer.Write(wrapper.ToString(TagRenderMode.EndTag));
            });
        }
    }
}