Grails Hql查询一对多关联

Question

我有一个培训领域课程

    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 
    }

现在我有一个过滤器（这是gsp页面，它会将id作为参数发送给控件），该过滤器根据课程和轨迹选择训练

现在说params.courseId = 1和3

所以我写查询

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

这是正确的ii获得所需的输出。

现在当我说我有轨道ID时，params.trackId = 1,2

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

这是行不通的..如何写正确的查询，我有上述关联。

Answer 1

区别在于您要查询一对多关联，即“许多”方面。

假设的HQL：

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

或条件：

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

Answer 2

我还没有进行更深入的研究，但是此查询的结果与您首先编写的查询相同

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)")