Hi,

you could use the search type name, just make sure that it return PageTypeName instead of the default implementation. For example, put this in your page type base class:

        public string SearchTypeName
        {
            get { return PageTypeName; }
        }

Optionally, you could try:

 .TermsFacetFor(x => ((PageData)x).PageTypeName)

and then fetch the result by:

.TermsFacetFor<PageData>(x => x.PageTypeName)