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 
    }

现在我有一个过滤器（gsp页面，它将id作为参数传递给控件），根据路线和轨道选择训练

现在说params.courseId = 1和3

所以我写了查询

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

这是正确的我得到了理想的输出。

现在当我说我有跟踪id的时候，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..如何在上面说过的关联中写出正确的查询。

Answer 1

区别在于您正在查询一对多关联，即“多方”。

假设HQL：

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

或标准：

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

Answer 2

我没有经历过更深入，但这个查询给出的结果与您先写的查询相同[/ p>]

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)")

Grails Hql查询一对多关联

2 个答案: