Grails --illegal尝试在Hql中取消引用收集错误

Question

我有一个培训域类

    class Training {

     String type
     Date createdOn
     Date modifiedOn

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

我有课程领域课程

     class Course {

          String name

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

和跟踪域类

    class Track {
        String name 
    }

我想根据曲目选择培训。

现在说我得到了跟踪ID，我想根据Track id

检索培训

我尝试过像这样的查询

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

它给出了

 illegal attempt to dereference collection

错误..因为我无法做t.course.tracks.id

帮助我编写正确的hql查询以获得培训，如果我有跟踪ID（比如1,2）

Answer 1

你能做的就是这个

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

问题是当你试图从一个到多个。

Answer 2

请在下面找到HQL以检索tracid 1＆amp;的所有培训。 2。

  

来自课程c，Track tr，Training t其中tr.courceid = c.courceid和   tr.trackid = c.tracid和tr.trackid in（1,2）