Get the RSS URL for an SPList or SPDocumentLibrary Programmatically

Background

Recently, I developed an RSS Reader Web Part which would take the RSS URL of a list to render its feeds. Very much like the out of the box Web Part, with the exception that it was AJAX enabled. I would post the details when I am finished.

An idea came to me that, wouldn’t it be nice to also allow users to just give the list URL rather than the RSS URL since that would reduce a few steps on the user’s side. I thought it would be just a matter of accessing the RssUrl property of the SPList object, but to my surprise, it was not to be. There is no such property in the API, so I decided to write my own function for it.

Let’s analyze the RSS URL of a list or a library. Whenever the user clicks on View RSS feed on a library, here is how SharePoint constructs the URL:

http://<server>/<site>/
   _layouts/listfeed.aspx?List=%7B14206B18%2DF68F%2D479B%2DBC84%2D15EE48D19D7D%7D

Listfeed.aspx is the inbuilt RSS viewer of SharePoint which accepts a parameter which is the GUID of the list. The %2D tokens refer to "-" characters which exist inside the GUID. Considering all this, it’s easy to write a function which will return the RSS URL. Here is the code for the same:

private string MakeRssUrl(string rawurl)
{
    try
    {
        Uri url = new Uri(rawurl, UriKind.Absolute);
        if (url.GetLeftPart(UriPartial.Path).Contains("_layouts/listfeed.aspx"))
        {
            return rawurl;
        }
        else
        {
             string rssurl;

             using (SPWeb web = new SPSite(rawurl).OpenWeb())
             {
                 SPList list = web.GetListFromUrl(rawurl);
                 rssurl = web.Url + "/_layouts/listfeed.aspx?list=" + list.ID;
                 return rssurl;
             }
        }
    }
    catch (UriFormatException e)
    {
        return string.Empty;
    }
}

The code is pretty self explanatory. The argument to the function is list URL or RSS URL. We first check if the URL is the RSS URL itself, and if it is, we just return. Otherwise, if it’s a list URL, we create an SPList instance, grab the GUID, and concatenate it with the site URL and listfeed.aspx.

Note that the function does not validate if the given URL is actually a valid list URL or not. The exception handling for that case should be left to the caller of the function.