Grails域中的瞬态属性

问题描述

我有一个名为People的Grails域名，我想检查每个People是否有子。孩子是别人的对象。这是我的域结构：

  class People实现可序列化{
 
 static constraints = {
 name（nullable：false，unique：true）
 createdBy（nullable：false）
 creationDate（nullable：false）
} 
 
 static transients = ['hasChild '] 
 
 static mapping = {
 table'PEOPLE'
 id生成器：​​'sequence'，params：[sequence：'SEQ_PK_ID'] 
 columns {
 id列：'APEOPLE_ID'
 parentPeople列：'PARENT_PEOPLE_ID'
} 
 parentPeople lazy：false 
} 
 
人员parentPeople 
字符串名称
字符串描述
 
 Boolean hasChild（）{
 def childPeoples = People.createCriteria（）。count {
 eq（'parentPeople'，People）
} 
 return（childPeoples> 0）
} 
} 
  

但是我无法在任何地方调用people.hasChild（）。你能请我帮忙吗非常感谢！

解决方案

这是因为在 eq（'parentPeople'，People），Grails不明白人是什么（这是一个类）。你应该用这个替换People。例如：

  static transients = [children] 
 
 def getChildren（）{
 def childPeoples = People.findAllByParentPeople（this，[sort：'id'，order：'asc']）
} 
  

I have a Grails domain called People, and I want to check that each People has childs or not. Childs are other People objects. Here is my domain structure:

class People implements Serializable {

    static constraints = {
        name (nullable : false, unique : true)
        createdBy (nullable : false)
        creationDate (nullable : false)
    }

    static transients = ['hasChild']

    static mapping = {
        table 'PEOPLE'
        id generator: 'sequence', params : [sequence : 'SEQ_PK_ID']
        columns {
            id column : 'APEOPLE_ID'
            parentPeople column : 'PARENT_PEOPLE_ID'
        }
        parentPeople lazy : false
    }

    People parentPeople
    String name
    String description

    Boolean hasChild() {
        def childPeoples = People.createCriteria().count { 
            eq ('parentPeople', People) 
        }
        return (childPeoples > 0)
    }
}

But I cannot call people.hasChild() at anywhere. Could you please helpe me on this? Thank you so much!

解决方案

It's because in eq ('parentPeople', People), Grails can't understand what "People" is (it's a class). You should replace "People" by this. For example:

static transients = ["children"]

    def getChildren() {
        def childPeoples = People.findAllByParentPeople(this, [sort:'id',order:'asc'])
    }

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