GRAILS：找到所有儿童的自我参照一对多关系 [英] GRAILS: Find all children in a self-referenced one-to-many relationship

问题描述

在grails中，

如何找到一对多关系中的所有孩子，例如，

  class Employee {
 static hasMany = [subordinates：Employee] 
 static belongsTo = [manager：Employee] 
} 
  

使用单个管理器，如何获取所有下属的下级（如遍历对象图）？

解决方案

如果您不想修改域，则递归闭包有效。否则，您可以在此示例中向 Employee 域类添加临时属性，如 allSubordinates 。

  class Employee {
字符串名称
 static hasMany = [subordinates：Employee] 
 static belongsTo = [manager：Employee ] 
 static transients = ['allSubordinates'] 
 def getAllSubordinates（）{
 return subordinates？下属* .allSubordinates.flatten（）+下属：[] 
} 
} 
  



<

  import grails.test。* 
 
类EmployeeTests扩展GrailsUnitTestCase {
雇员ceo 
雇员middleManager1，middleManager2 
雇员e1，e2，e3，e4，e5，e6 
 
保护void setUp（）{ 
 super.setUp（）
 ceo =新员工（名称：CEO）
 middleManager1 =新员工（名称：中间经理1）
 e1 =新员工名称：e1）
 e2 =新员工（名称：e2）
 e3 =新员工（名称：e3）
 middleManager2 =新员工（名称： 2）
 e4 =新员工（姓名：e4）
 e5 =新员工（姓名：e5）
 e6 =新员工（姓名：e6）
 
 ceo.subordinates = [middleManager1，middleMan ager2] 
 middleManager1.subordinates = [e1，e2，e3] 
 middleManager2.subordinates = [e4，e5，e6] 
 assert ceo.save（）
} 
 
 void testAllSubordinates（）{
 def topLevelManager = Employee.get（ceo.id）
 assertNotNull（topLevelManager）; 
 assertEquals（8，topLevelManager.allSubordinates？.size（））
} 
} 
  




In grails,

How would one find all the children in a one-to-many relationship e.g.,

class Employee {
    static hasMany = [ subordinates: Employee ]
    static belongsTo = [ manager: Employee ]
}

Using a single manager, how would one get the subordinates of all subordinates (like traversing a object graph)?

解决方案

The recursive closure works if you don't want to modify the domain. Otherwise you could add a transient property to the Employee domain class like allSubordinates in this example:

class Employee {
    String name
    static hasMany = [ subordinates: Employee ]
    static belongsTo = [ manager: Employee ]
    static transients = ['allSubordinates']
    def getAllSubordinates() {
        return subordinates ? subordinates*.allSubordinates.flatten() + subordinates : []
    }
}

Here is an integration test to see it in action:

import grails.test.*

class EmployeeTests extends GrailsUnitTestCase {
    Employee ceo
    Employee middleManager1, middleManager2
    Employee e1, e2, e3, e4, e5, e6

    protected void setUp() {
        super.setUp()
        ceo = new Employee(name:"CEO")
            middleManager1 = new Employee(name:"Middle Manager 1")
                e1 = new Employee(name:"e1")
                e2 = new Employee(name:"e2")
                e3 = new Employee(name:"e3")
            middleManager2 = new Employee(name:"Middle Manager 2")
                e4 = new Employee(name:"e4")
                e5 = new Employee(name:"e5")
                e6 = new Employee(name:"e6")

        ceo.subordinates = [middleManager1, middleManager2]
        middleManager1.subordinates = [e1,e2,e3]
        middleManager2.subordinates = [e4,e5,e6]
        assert ceo.save()
    }

    void testAllSubordinates() {
        def topLevelManager = Employee.get(ceo.id)
        assertNotNull(topLevelManager);
        assertEquals(8, topLevelManager.allSubordinates?.size())
    }
}

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