Create RSS feed in MVC4/WebAPI - rss

Question

I'm looking for the best way to create an RSS feed via MVC4 (and/or WebAPI). This post seemed the most applicable http://www.strathweb.com/2012/04/rss-atom-mediatypeformatter-for-asp-net-webapi/. But it was written in the pre-Release days of WebAPI. I've used Nuget to bring all packages up-to-date but attempting to build the project tosses:
Error 2 The type or namespace name 'FormatterContext' could not be found (are you missing a using directive or an assembly reference?) G:\Code\MvcApplication-atomFormatter\MvcApplication-atomFormatter\SyndicationFeedFormatter.cs 38 129 MvcApplication_syndicationFeedFormatter
I've found a number of articles explaining that the MediaTypeFormatter has changed significantly since beta but I have found details on the adjustments required to the code snippet in question.
Is there an updated resource showing the construction of an RSSFormatter?
thx

Answer 1

Yes I wrote that tutorial against Beta.
Below is the code updated to RTM version.
One advice, if I may, is that this example uses a simple "whitelist" of concrete types for which RSS/Atom feed is build (in this case my Url model). Ideally in more complex scenarios, you'd have the formatter set up against an interface, rather than a concrete type, and have all Models which are supposed to be exposed as RSS to implement that interface.
Hope this helps.
public class SyndicationFeedFormatter : MediaTypeFormatter
{
private readonly string atom = "application/atom+xml";
private readonly string rss = "application/rss+xml";
public SyndicationFeedFormatter()
{
SupportedMediaTypes.Add(new MediaTypeHeaderValue(atom));
SupportedMediaTypes.Add(new MediaTypeHeaderValue(rss));
}
Func<Type, bool> SupportedType = (type) =>
{
if (type == typeof(Url) || type == typeof(IEnumerable<Url>))
return true;
else
return false;
};
public override bool CanReadType(Type type)
{
return SupportedType(type);
}
public override bool CanWriteType(Type type)
{
return SupportedType(type);
}
public override Task WriteToStreamAsync(Type type, object value, Stream writeStream, System.Net.Http.HttpContent content, System.Net.TransportContext transportContext)
{
return Task.Factory.StartNew(() =>
{
if (type == typeof(Url) || type == typeof(IEnumerable<Url>))
BuildSyndicationFeed(value, writeStream, content.Headers.ContentType.MediaType);
});
}
private void BuildSyndicationFeed(object models, Stream stream, string contenttype)
{
List<SyndicationItem> items = new List<SyndicationItem>();
var feed = new SyndicationFeed()
{
Title = new TextSyndicationContent("My Feed")
};
if (models is IEnumerable<Url>)
{
var enumerator = ((IEnumerable<Url>)models).GetEnumerator();
while (enumerator.MoveNext())
{
items.Add(BuildSyndicationItem(enumerator.Current));
}
}
else
{
items.Add(BuildSyndicationItem((Url)models));
}
feed.Items = items;
using (XmlWriter writer = XmlWriter.Create(stream))
{
if (string.Equals(contenttype, atom))
{
Atom10FeedFormatter atomformatter = new Atom10FeedFormatter(feed);
atomformatter.WriteTo(writer);
}
else
{
Rss20FeedFormatter rssformatter = new Rss20FeedFormatter(feed);
rssformatter.WriteTo(writer);
}
}
}
private SyndicationItem BuildSyndicationItem(Url u)
{
var item = new SyndicationItem()
{
Title = new TextSyndicationContent(u.Title),
BaseUri = new Uri(u.Address),
LastUpdatedTime = u.CreatedAt,
Content = new TextSyndicationContent(u.Description)
};
item.Authors.Add(new SyndicationPerson() { Name = u.CreatedBy });
return item;
}
}