Grails Hql query for one to many association

Question

I have a Training domain class

    class Training {

     String type
     Date createdOn
     Date modifiedOn

    static belongsTo = [course: Course]
    static hasMany = [attachments: Attachment]
  }

and i have Course domain class

     class Course {

          String name

          static hasMany = [trainings: Training, tracks: Track]
          static belongsTo = Track
   }

and Track domain class

    class Track {
        String name 
    }

Now i have a filter (which is gsp page wich sends id's as a params to the control) that selects the training based on course and track

now say params.courseId = 1 and 3

so i write the query

   def query = "FROM Training AS t WHERE  t.course.id IN (1,3)"
   trainingList = Training.findAll(query)

which is correct i i get desired output.

now when i say i have track id's , params.trackId = 1,2

    def query = "FROM Training AS t WHERE  t.course.tracks.id IN (1,2)"
    trainingList = Training.findAll(query) 

which is not working.. how to write the correct query where i have above said association.

Answer 1

The difference is your're querying one-to-many association, the "many" side.

Supposed HQL:

def query = "FROM Training AS t WHERE exists " +
  "(from t.course.tracks AS tr where tr.id IN (1,2))"

or criteria:

def trainings = Training.withCriteria {
   course {
     tracks {
       in('id', [1, 2])
     }
  }
}

Answer 2

I haven't went through much deeper but this query giving the same result like the query you written first

def trainingList = Training.findAll ("from Training as trnin "+
"join trnin.course.id as trinincr"+
"join trinincr.tracks.id"+
" where trnin.course.id in (1,3)")