从自引用表获取Laravel ORM中其他表的列，获取N级层次结构JSON [英] Get column of other table in Laravel ORM from self referencing table get N level hierarchy JSON

问题描述

我有两个表abc和def.我有这两个表的模型，分别命名为Abc和Def.在Abc中，我声明了以下两个函数:

I have two tables abc and def. I have models of these two tables named respectively Abc and Def. In Abc, I declare these two functions:

public function child()
{
   return $this->hasMany('Abc', 'parent');
}

// recursive, loads all descendants
public function children()
{
   return $this->child()->with('children')->orderBy('sort_order');  
}

// parent
public function parent()
{
   return $this->belongsTo('Abc','parent');
}

// all ascendants
public function parentRecursive()
{
   return $this->parent()->with('parentRecursive');
}

在控制器中，我通过以下方式调用了这些功能

In controllers I called these functions by

$abc = Abc::with('children')->whereNull('parent')->get();

我已经通过父子关系从表实现了层次结构JSON.我在两个表中都有通用的列名.通过这些方法，我获得了abc表的标题列.但是我想获取def表的标题列.我们该怎么做?

I have implemented level hierarchy JSON from table through parent child relation. I have common column name in both tables. Through these method I get the title column of abc table. But I want to fetch title column of def table. How we can do this?

推荐答案

使用关系:

// Abc model
public function defs()
{
  return $this->hasMany('Def', 'abc_id');
}

public function childrenWithDef()
{
  return $this->child()->with('childrenWithDef.defs')->orderBy('sort_order');
}

// then:
$abc = Abc::with('childrenWithDef', 'defs')->whereNull('parent')->get();

// every Abc has related Def collection
foreach ($abc->first()->defs as $def) $def->title

或手动加入该关系并选择所需的任何内容:

or manually joining on the relation and selecting whatever you need:

public function childrenWithTitle()
{
   return $this->child()->with('children')->orderBy('sort_order')
     ->leftJoin('defs', 'defs.abc_id', '=', 'abcs.id')->select('abc.*', 'def.title');
}

请记住，您需要选择键/外键，以便雄辩地将孩子与父母配对！

Remember that you need keys/foreign keys to be selected in order to let Eloquent match children to their parents!

$abc = Abc::with('childrenWithTitle')->whereNull('parent')->leftJoin(...)->first();
$abc->childrenWithTitle->first()->title; // 'title' or null if no row found for this child

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