Link Database

Sometimes it is required to get all Items in the database based on a given template. Iterating through the entire database may be a very expensive operation though.

However in this particular case, we can resort to the Link database. Link database is used by Sitecore to resolve all the linking issues - what referrers and what references the Item has. And if an item is based on a template, it also counts as a reference from the item to the template. The solution then is very simple: get all the referrers for a given template item.

Below you can see how Link Database is used in the RSS module architecture:

private static Item[] GetFeedsInDatabase(Database database, Language language)
{
   TemplateItem feedTemplate = database.Templates[Constants.FeedTemplateID];
   if (feedTemplate == null)
   {
      return null;
   }
   // Get all items refering to the feed template
   ItemLink[] links = Globals.LinkDatabase.GetReferers(feedTemplate.InnerItem);
   if (links == null)
   {
      return null;
   }
   ArrayList result = new ArrayList(links.Length);
   // and filter the referers - we dont need to include masters
   foreach(ItemLink link in links)
   {
      if (link.SourceDatabaseName == database.Name)
      {
         Item item = database.Items[link.SourceItemID, language];
         if ((item != null) && (IsMaster(item) == false))
         {
            result.Add(item);
         }
      }
   }
   return (Item[])result.ToArray(typeof(Item));
}