I am trying to construct a criteria that will provide an AVG of a field from the returned set of objects from a search.
The first part of the criteria works fine. The restriction on type.
But I can't get the avg function to return a single result. I get an error on the execution of the getSingleResult() method that there are multiple rows.

So, I have the search and the criteria as follows:

Session session = (Session) getDao().getEntityManager().getDelegate();
Criteria query = session.createCriteria(Tattle.class, "t");
query.add( Restrictions.eq("t.type", "tattle"));
query.setProjection( Projections.projectionList().add( Projections.avg( "t.points" )));

luceneQuery = parser.parse("text:" + searchQuery + " OR " + "subject:" + searchQuery);
fq = fullTextEntityManager.createFullTextQuery(luceneQuery).setCriteriaQuery( query );

// run the search query
averageRating = (Long)fq.getSingleResult();

Mixing and matching Lucene queries (fulltext queries) with Hibernate Criteria queries is not supported. The documentation uses Criteria to specify a fetch type, but otherwise recommends against applying additional criteria.

--Hardy