PageNotFoundContentFinder.cs

using System.Linq;
using Umbraco.Core;
using Umbraco.Core.Logging;
using Umbraco.Web;
using Umbraco.Web.Routing;

namespace uComponents.ContentFinders
{
	public class PageNotFoundContentFinder : IContentFinder
	{
		public bool TryFindContent(PublishedContentRequest contentRequest)
		{
			if (contentRequest == null)
				return false;

			LogHelper.Debug<PageNotFoundContentFinder>("TryFindContent({0})", () => contentRequest.Uri.ToString());

			// get all the content nodes that have a property value for 'umbracoPageNotFound'
			// sort them in descending order (by @level), then select the first one that has the closest URL/path.

			var path = contentRequest.Uri.GetAbsolutePathDecoded();
			var xpath = "descendant::*[@isDoc and normalize-space(umbracoPageNotFound)]";
			var node = contentRequest
				.RoutingContext
				.UmbracoContext
				.ContentCache
				.GetByXPath(xpath, null)
				.OrderByDescending(x => x.Level)
				.FirstOrDefault(x => path.IndexOf(x.Url) >= 0);

			if (node == null)
				return false;

			var pageNotFoundId = node.GetPropertyValue<int>("umbracoPageNotFound");
			if (pageNotFoundId <= 0)
				return false;

			var pageNotFound = contentRequest.RoutingContext.UmbracoContext.ContentCache.GetById(pageNotFoundId);
			if (pageNotFound == null)
				return false;

			contentRequest.PublishedContent = pageNotFound;
			contentRequest.SetIs404();

			return true;
		}
	}
}