循环遍历一个数组，同时添加一个基于另一个值的新键：值对

Question

我在多级数组中有以下数据

1: id: 41, parent: null, name: lucas
2: id: 52, parent: null, name: george
3: id 98: parent: 41, name: julian
...

我需要遍历这个数组和一个'childrens' 键和值到父级，同时每次我运行一个“父级”未设置为空的条目时对该值求和+1。如何做到这一点？

1: id: 41, parent: null, name: lucas, children: 1

我在 foreach 中尝试过这个

foreach($post as $parsedPost) {
    if($parsedPost['parent'] > 0){
        $idChild = $parsedPost['id'];
        $idParent = $parsedPost['parent'];
        $post[$idParent]["childrens"]++;
    }
 }

当然，它会返回一个通知，因为索引['childrens'] 不存在。此外，它将childrens:value 添加到第一个孩子而不是父母。 为什么？

Answer 1

希望这会有所帮助。

$post[] = ["id" => "41", "parent" => null, "name" => "lucas"];
$post[] = ["id" => "52", "parent" => null, "name" => "george"];
$post[] = ["id" => "98", "parent" => "41", "name" => "Julian"];

foreach ($post as $parsedPost)
{
    if ($parsedPost['parent'] > 0 && $parsedPost['parent'] != "")
    {
        $idChild = $parsedPost['id'];
        $idParent = $parsedPost['parent'];
        $parentKey = array_search($idParent,array_column($post,'id'));
        if(!isset($post[$parentKey]["childrens"]))
        {
            $post[$parentKey]["childrens"] = 0;
        }
        $post[$parentKey]["childrens"]++;
    }
}
print_r($post);

输出：

Array
(
    [0] => Array
        (
            [id] => 41
            [parent] => 
            [name] => lucas
            [childrens] => 1
        )

    [1] => Array
        (
            [id] => 52
            [parent] => 
            [name] => george
        )

    [2] => Array
        (
            [id] => 98
            [parent] => 41
            [name] => Julian
        )

)