Grails领域类与它自己的关系 [英] Grails domain class relationship to itself

问题描述

我需要一种能够让域类有很多自己的方法。换句话说，有一个父母和孩子的关系。我正在处理的表中有数据，然后是一个名为parent_id的列。如果任何项目设置了parent_id，则它是该元素的子项。

I need a way to be able to have a domain class to have many of itself. In other words, there is a parent and child relationship. The table I'm working on has data and then a column called "parent_id". If any item has the parent_id set, it is a child of that element.

有没有什么方法可以让Grails告诉hasMany哪个字段需要引用？

Is there any way in Grails to tell hasMany which field to look at for a reference?

推荐答案

这是你正在寻找的一个例子（这是我正在运行的代码段代码，它会生成列parent_id）。我不认为你需要SortedSet：

This is an example of what you are looking for (it's a snippet code I am running and it generates column parent_id). I don't think you need SortedSet:

class NavMenu implements Comparable { 
    String category
    int rank = 0

    String title
    Boolean active = false

    //NavMenu parent
    SortedSet subItems
    static hasMany = [subItems: NavMenu]
    static belongsTo = [parent: NavMenu]
  }

另外，你可以使用Mapping DSL命名hasMany子句，在 http://grails.org/GORM+ - + Mapping + DSL

Furthermore, you can give name to the hasMany clause using the Mapping DSL, which is explained at http://grails.org/GORM+-+Mapping+DSL

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