Rss feed formatter ActionResult for ASP.NET MVC

gistfile1.txt

using System;
using System.IO;
using System.Linq;
using System.ServiceModel.Syndication;
using System.Text;
using System.Web.Mvc;
using System.Xml;
using System.Xml.Linq;



    public abstract class SyndicationFeedResult<TFeedFormatter> : ActionResult where TFeedFormatter : SyndicationFeedFormatter
    {
        public SyndicationFeed Feed { get; set; }  
        
        protected TFeedFormatter Formatter;
        protected XmlWriterSettings WriterSettings;

        protected SyndicationFeedResult(SyndicationFeed feed)
        {
            Feed = feed;
        }

        public abstract TFeedFormatter ConstructFeedFormatter();
        public abstract XmlWriterSettings ConfigureXmlWriter();
        public abstract string ConfigureOutputContentType();
        public abstract void PostProcessOutputBuffer(StringBuilder buffer);

        public override void ExecuteResult(ControllerContext context)
        {
            Formatter = ConstructFeedFormatter();
            WriterSettings = ConfigureXmlWriter();
            context.HttpContext.Response.ContentType = ConfigureOutputContentType();

            var buffer = new StringBuilder();
            var cachedOutput = new StringWriter(buffer);

            using (var writer = XmlWriter.Create(cachedOutput, WriterSettings))
            {
                if (writer != null)
                {
                    Formatter.WriteTo(writer);
                    writer.Close();
                }
            }

            PostProcessOutputBuffer(buffer);

            context.HttpContext.Response.Output.Write(buffer.ToString());
        }
    }   


public class RssResult : SyndicationFeedResult<Rss20FeedFormatter>
    {
        public RssResult(SyndicationFeed feed)
            : base(feed)
        {
        }

        public override Rss20FeedFormatter ConstructFeedFormatter()
        {
            return new Rss20FeedFormatter(Feed);
        }

        public override XmlWriterSettings ConfigureXmlWriter()
        {
            return new XmlWriterSettings
            {
                NewLineHandling = NewLineHandling.None,
                Indent = true,
                Encoding = Encoding.UTF32,
                ConformanceLevel = ConformanceLevel.Document,
                OmitXmlDeclaration = true
            };
        }

        public override string ConfigureOutputContentType()
        {
            return "application/xml";
        }

        public override void PostProcessOutputBuffer(StringBuilder buffer)
        {
            var xmlDoc = XDocument.Parse(buffer.ToString());
            foreach (var element in xmlDoc.Descendants("channel").First().Descendants("item").Descendants("description"))
            {
                VerifyCdataHtmlEncoding(buffer, element);
            }

            foreach (var element in xmlDoc.Descendants("channel").First().Descendants("description"))
            {
                VerifyCdataHtmlEncoding(buffer, element);
            }

            buffer.Replace(" xmlns:a10=\"http://www.w3.org/2005/Atom\"", " xmlns:atom=\"http://www.w3.org/2005/Atom\"");
            buffer.Replace("a10:", "atom:");
        }

        private static void VerifyCdataHtmlEncoding(StringBuilder buffer, XElement element)
        {
            if (!element.Value.Contains("<") || !element.Value.Contains(">"))
            {
                return;
            }

            var cdataValue = string.Format("<{0}><![CDATA[{1}]]></{2}>", element.Name, element.Value, element.Name);
            buffer.Replace(element.ToString(), cdataValue);
        }
    }