Hello,

What version of Kentico CMS do you use? Any hotfixes?

Basically, you can use following expression:

<%# IfEmpty(Eval("DocumentTags"),"","Filed under: " + BlogFunctions.GetDocumentTags(Eval("DocumentTagGroupID"), Eval("DocumentTags"), "~/page.aspx")) %>

The above code shows document tags from Tag selector field for particular document. The last parameter tells where you should be redirected to. On page.aspx will be repeater with WHERE condition to show tags just of appropriate TagId.

More details can be found here: Using the tag cloud webpart

Also, if you install Corporate Site sample site, you can see it in action with Blog posts. Please focus on CMS.BlogPost.Default transformation.

Best regards
Ondrej Vasil