how to get distinct results using Projections and Criteria

Question

I am trying to load distinct Parents using Criteria in Grails. The query is as following

Query:

def criteria = Parent.createCriter         


        

Answer 1

You can achieve the same effect as with criteria.listDistinct if you change the criteria query to include distinct root entity results transformer like this:

    results =  criteria.list(max:params.max, offset:params.offset){
        children{
            books{
                like('title',"%book")
                }
            }
         resultTransformer Criteria.DISTINCT_ROOT_ENTITY            
         order("id","asc")
    }

There is however a reason why grails does not return paged results for the listDistinct call so it might be a case to resort to an HQL query with the in operator