HtmlHelperExtensions.cs

using System.Collections.Generic;
using System.Text;
using System.Web;
using System.Web.Mvc;
using System.Web.Mvc.Html;
using Umbraco.Core.Logging;
using Umbraco.Core.Models;

namespace Foo
{
    public static class HtmlHelperExtensions
    {
        public static IHtmlString RenderNestedContentPartials(this HtmlHelper htmlHelper, IEnumerable<IPublishedContent> contentList, string partialPath, ViewDataDictionary viewDataDictionary)
        {
            if (contentList == null)
            {
                return new MvcHtmlString("");
            }

            var sb = new StringBuilder();

            foreach (var content in contentList)
            {
                sb.AppendLine(_renderPartial(htmlHelper, content, partialPath, viewDataDictionary).ToString());
            }

            return new HtmlString(sb.ToString());
        }

        private static IHtmlString _renderPartial(HtmlHelper htmlHelper, IPublishedContent content, string partialPath, ViewDataDictionary viewDataDictionary)
        {
            var context = HttpContext.Current;

            if (content == null || context == null)
            {
                return new HtmlString("");
            }

            var sb = new StringBuilder();

            //default
            var pathToPartials = "~/Views/Partials/NestedContent/";

            if (!string.IsNullOrEmpty(partialPath))
            {
                pathToPartials = partialPath;
            }

            var partial = string.Format("{0}{1}.cshtml", pathToPartials, content.DocumentTypeAlias);

            if (System.IO.File.Exists(context.Server.MapPath(partial)))
            {
                sb.AppendLine(htmlHelper.Partial(partial, content, viewDataDictionary).ToString());
            }
            else
            {
                LogHelper.Info<IPublishedContent>(string.Format("The partial for {0} could not be found.  Please create a partial with that name or rename your alias.", context.Server.MapPath(partial)));
            }

            return new HtmlString(sb.ToString());
        }
    }
}