Hooking into the Lucene events with Umbraco

ConfigureLuceneIndexing.cs

using System.Web.UI;
using Examine;
using Examine.LuceneEngine;
using Examine.LuceneEngine.Providers;
using Umbraco.Core;
using Umbraco.Web;

namespace AMAZINGWEBSITE.Web.Core.ApplicationEventHandlers
{
    public class ConfigureLuceneIndexing : IApplicationEventHandler
    {
        public void OnApplicationInitialized(UmbracoApplicationBase umbracoApplication, ApplicationContext applicationContext)
        {
        }

        public void OnApplicationStarting(UmbracoApplicationBase umbracoApplication, ApplicationContext applicationContext)
        {
        }

        public void OnApplicationStarted(UmbracoApplicationBase umbracoApplication, ApplicationContext applicationContext)
        {
            var indexer = ExamineManager.Instance.IndexProviderCollection["ExternalIndexer"];
            var luceneIndexer = indexer as LuceneIndexer;
            if (luceneIndexer != null) luceneIndexer.DocumentWriting += OnDocumentWriting;
        }

        private static void OnDocumentWriting(object sender, DocumentWritingEventArgs e)
        {
            // cancel the indexing of anything that isn't underneath the homepage (which has ID 1056)
            if (!e.Fields["path"].StartsWith("-1,1056"))
            {
                e.Cancel = true;
                return;
            }

            // boost the following doctypes
            var docType = e.Fields["nodeTypeAlias"];

            switch (docType)
            {
                case "MyBoostedDocTypeAlias":
                    e.Document.SetBoost(30f);
                    break;
            }
        }
    }
}

Another use case here is to attach additional information to your Lucene document, so that node becomes searchable by your attributed data.