php - 按父级对 Eloquent 集合进行排序

Question

这是我的标签表:

id      name        parent
--------------------------
1      parent1      null
2      a            parent1
3      b            parent1
4      parent2      null
5      c            parent2
6      d            parent1
7      parent3      null
8      e            parent3
9      f            parent2

我怎样才能拥有一个集合，每个标签都放在其父标签下？我的意思是:

Collection {#499 ▼
  #items: array:22 [▼
    0 => tag {#524 ▶} //parent1
    1 => tag {#525 ▶} //a
    2 => tag {#526 ▶} //b
    3 => tag {#527 ▶} //d
    4 => tag {#528 ▶} //parent2
    5 => tag {#529 ▶} //c
    6 => tag {#530 ▶} //f
    7 => tag {#530 ▶} //parent3
    8 => tag {#530 ▶} //e
  ]
}

谢谢。

Answer 1

给定一个模型 Item与自身的关系:

class Item extends model {
    public function children() {
         // parent being a foreign key
         return $this->hasMany(__CLASS__, 'parent', 'id');
    }
}

$items = Item::with('children')->get();