SyndicationFeed: Content as CDATA?

问题:

I'm using .NET's SyndicationFeed to create RSS and ATOM feeds. Unfortunately, I need HTML content in the description element (the Content property of the SyndicationItem) and the formatter automatically encodes the HTML, but I'd rather have the entire description element wrapped in CDATA without encoding the HTML.

My (simple) code:

var feed = new SyndicationFeed("Title", "Description", 
               new Uri("http://someuri.com"));
var items = new List<SyndicationItem>();

var item = new SyndicationItem("Item Title", (string)null, 
               new Uri("http://someitemuri.com"));

item.Content = SyndicationContent.CreateHtmlContent("<b>Item Content</b>");

items.Add(item);
feed.Items = items;

Anybody an idea how I can do this using SyndicationFeed? My last resort is to "manually" create the XML for the feeds, but I'd rather use the built-in SyndicationFeed.

回答1:

This worked for me:

public class CDataSyndicationContent : TextSyndicationContent
{
    public CDataSyndicationContent(TextSyndicationContent content)
        : base(content)
    {}

    protected override void  WriteContentsTo(System.Xml.XmlWriter writer)
    {
        writer.WriteCData(Text);
    }
}

then you can:

new CDataSyndicationContent(new TextSyndicationContent(content, TextSyndicationContentKind.Html))

回答2:

For those for whom the solution provided by cpowers and WonderGrub also didn't work, you should check out the following SO question, because for me this question was actually the answer to my occurence of this problem! Rss20FeedFormatter Ignores TextSyndicationContent type for SyndicationItem.Summary

Judging from the positive answer from thelsdj and Andy Rose and then later the 'negative' response from TimLeung and the alternative offered by WonderGrub I would estimate that the fix offered by cpowers stopped working in some later version of ASP.NET or something.

In any case the solution in the above SO article (derived from David Whitney's code) solved the problem with unwanted HTML encoding in CDATA blocks in an RSS 2.0 feed for me. I used it in an ASP.NET 4.0 WebForms application.

回答3:

This should work.

item.Content =  new TextSyndicationContent("<b>Item Content</b>",TextSyndicationContentKind.Html);

回答4:

I had the same problem as some where the WriteContentsTo override wasn't being called in cpowers example (still no idea why). So, I changed it to inherit from the SyndicationContent class instead. Not sure if this is the best solution, but worked great in my situation.

public class CDataSyndicationContent : SyndicationContent
{
    public CDataSyndicationContent(string content)
    {
        Text = content;
    }

    public override SyndicationContent Clone()
    {
        return new CDataSyndicationContent(Text);
    }

    public override string Type
    {
        get { return "html"; }
    }

    public string Text { get; private set; }

    protected override void WriteContentsTo(XmlWriter writer)
    {
        writer.WriteCData(Text);
    }
}

回答5:

try this

XmlReaderSettings settings = new XmlReaderSettings();
            settings.IgnoreComments = false;
            //settings.ProhibitDtd = false;
            using (XmlReader reader = XmlReader.Create(rssurl, settings))

回答6:

Here is what we did :

public class XmlCDataWriter : XmlTextWriter
       {
           public XmlCDataWriter(TextWriter w): base(w){}

           public XmlCDataWriter(Stream w, Encoding encoding): base(w, encoding){}

           public XmlCDataWriter(string filename, Encoding encoding): base(filename, encoding){}

           public override void WriteString(string text)
           {
               if (text.Contains("<"))
               {
                   base.WriteCData(text);
               }
               else
               {
                   base.WriteString(text);
               }
           }

       }

And then to use the class :

public StringBuilder CDataOverwiriteMethod(Rss20FeedFormatter formatter)
       {
           var buffer = new StringBuilder();

           //could be streamwriter as well
           using (var stream = new StringWriter(buffer))
           {
               using (var writer = new XmlCDataWriter(stream))
               {
                   var settings = new XmlWriterSettings() {Indent = true};

                   using (var xmlWriter = XmlWriter.Create(writer, settings))
                   {
                       formatter.WriteTo(xmlWriter);
                   }
               }
           }

           return buffer;
       }

回答7:

It might be too late but I leave my solution. I added it as a ElementExtension then it works for me. My environment is .NET 4.5.

XNamespace nsDefault = "http://www.w3.org/2005/Atom";
var content = new XElement(nsDefault + "content");
content.Add(new XCData("<b>Item Content</b>"));
item.ElementExtensions.Add(new SyndicationElementExtension(content));

回答8:

The shortest way to do this is:

.Content = SyndicationContent.CreateXhtmlContent("<![CDATA[The <em>content</em>]]>")

That will be outputted in the XML as

<entry>
  …
  <content type="xhtml"><![CDATA[The <em>content</em>]]></content>
  …
</entry>

Not an elegant solution, I admit, but it works properly – just tried on a project of mine.

回答9:

try

item.Content = "<![CDATA[" + 
            SyndicationContent.CreateHtmlContent("<b>Item Content</b>") + "]]>";