Is there a way to use the "select new map" when using Criteria to execute a query?

The "select new map" is perfect for what I want to do. I just need a few fields returned some of which may be nested deeply in the tables, and I don't have classes for the underlying tables.

"select new map" works fine when I use a Query. My problem is that my application has a search page with a bunch of fields that the user can enter values for that will end up in the where clause. If they do not enter a value for a field the param associated with that field should not be included in the where. If I use Query for this, I will get an exception that all parameters are not set. I'm not real keen on building the queryString dynamically. Criteria works real well for this. If the field is null, I don't add a Restriction on the Criteria for that field.

So "select new map" with Criteria will do the trick for me. Can it be done?

Not really. Criteria queries load objects, not groups of scalars. You can force scalar results through clever use of projections. For example, if you select max(field) on a Criteria where you're specifying the id (so only one row is going to be returned), then you get the field value (max value of all one values is the value). However, this is very inefficient, compared to the HQL equivalent.

Report queries are best done as HQL or SQL.

I think that I can use Filter with Query to do the trick

criteria supports report querying just a good as HQL/SQL.

to have "select new" functionallity look at resulttransformer API (we also have a blog about - search for transformer)