How to use Hibernate Spatial in HQL queries?

Question

How to use Hibernate Spatial in HQL queries?

I want to use Hibernate Spatial in Hibernate 3.6 HQL queries. I have the following domain class:

import com.vividsolutions.jts.geom.Point

class Book {

  String title 
  Point location

  static constraints = {
    location nullable: true
  }
}

I can make the following request:

    def filter = reader.read('POLYGON ((0 0, 0 10, 10 10, 10 0, 0 0))')

    def session2 = sessionFactory.currentSession
    def q = session2.createQuery("from Book b where within(location, ?) = true")
    q.setParameter(0, filter, GeometryUserType.TYPE)
    println (q.list())

The former works great. Now I want to write it something like this:

   def queryParams = [:]
    queryParams.loc = filter

    List<Book> results = new ArrayList<>()

    def query =
    """
    select b from Book b 
    where within(b.location, :loc) = true  
    """

    results = Book.executeQuery(query, queryParams)