Thursday, 23 April 2009

Looking for a URL using Linq and SiteMaps

I've been off sick from work with Man Flu but this afternoon I was getting bored of staying in bed for the second day so I got out my laptop just to have a play in between blowing my nose.

I wanted to write a quick way of looking up the full url path for a page within a sitemap. The only bit of information I know is the key of the page. Now I knew that I could possibly make use of the IndexOf method. This expects a SiteMapNode of the value you are looking for and returns the index of the node, you then need to get the node out of your collection of nodes, example below.

SiteMapNodeCollection nodes = SiteMap.RootNode.GetAllNodes();
int nodeIndex = nodes.IndexOf(new SiteMapNode(SiteMap.Provider, pagekey));
return nodes[nodeIndex].Url ?? String.Empty;

Now that method does work, however it felt dead clunky, I was sure I could write a more .Net 3.5 shiny one line way of doing this using Linq. In fact it was dead easy. First I still needed to get all the nodes, SiteMap.RootNode.GetAllNodes(), but I then cast these to SiteMapNode, I could then use FirstOrDefault with a nice lambda expression that matches the key property. Code below.

SiteMapNode node = SiteMap.RootNode.GetAllNodes().Cast().FirstOrDefault(n => n.Key.Equals(pagekey));
return node != null ? node.Url : String.Empty;
//note: the </sitemapnode> is not part of the code, the code highlighter JS is randomly adding it.

Simple, my only concern is that the bigger the sitemap becomes the more memory / slower this becomes, especially if called multiple times per page. It may make sense to cache the sitemapnodecollection for the duration of the page however that's beyond the scope of this brief article.

What hopefully you can see though is that a little bit of Linq and Lambda expressions can take chunks of code that seem long winded and turn them into nice neat one liners, which I think is usually more readable.

1 comment:

  1. How about...

    SiteMapNode node = SiteMap.Provider.FindSiteMapNodeFromKey(pagekey);