在 PHP 中满足某个条件时如何停止递归循环

Question

我有一个以下结构的数组，我想将元素从根级别获取到第 3 级

Array
(
 [0] => Array
  (
   [id] => 1
   [parent_id] => 
   [name] => try 
   [sub_categories] => Array
    (
     [0] => Array
      (
       [id] => 2
       [parent_id] => 1
       [name] => try1
       [sub_categories] => Array
        (
         [0] => Array
          (
           [id] => 3
           [parent_id] => 2
           [name] => try2
           [sub_categories] => Array
            (
             [0] => Array
              (
               [id] => 4
               [parent_id] => 3
               [name] => try3
               [sub_categories] => Array
                (
                 [0] => Array
                  (
   

               [id] => 5
                  [parent_id] => 4
                  [name] => try4
                 )

               )

             )

           )

         )

       )

     )

   )
   
       (
    [1] => Array
     (
      [id] => 6
      [parent_id] => 1
      [name] => try1
      [sub_categories] => Array
       (
        [0] => Array
         (
          [id] => 7
          [parent_id] => 6
          [name] => try2
          [sub_categories] => Array
           (
            [0] => Array
             (
              [id] => 8
              [parent_id] => 7
              [name] => try3
              [sub_categories] => Array
               (
                [0] => Array
                 (
                  [id] => 9
                  [parent_id] => 8
                  [name] => try4
                 )

               )

             )

           )

         )

       )

     )

   )

 )

)

public function getElements( $parent_id = NULL, $level = 0 ) {

    $data = models\Categories::find()->where( ['parent_id'=>$parent_id] )->all();
    $arr = array();
    foreach( $data as $data ) {
        if( $level == 3 ) {
            break;
        }
        //do something
        $countChilds = models\Categories::find()->where( ['parent_id'=>$data->id] )->count();
        if( $countChilds > 0 ){
            $catData['sub_categories'] = $this->getElements( $parent_id = $data->id, $level++ );
        }
        $arr[] = $catData;
    }
    return $arr;
}

我尝试添加一个计数器并在计数器变为 3 时跳出循环但它不起作用，所以我认为因为计数器只能在根类别旁边的直接子类别上工作，因为我想下到树 3 层，所以计数器不工作什么是实现这一目标的最佳方法我希望我的结果数组输出一个 ID 为 1,2,3,4 , 6,7 的数组， 8. ID 为 5,9 的元素不应打印，因为它们属于级别 4

对此的任何帮助将不胜感激

Answer 1

<?php

public function getElements( $parent_id = NULL, $level = 0 ) {
    if( $level == 3 ) return []; // or return $arr;
    $data = models\Categories::find()->where( ['parent_id'=>$parent_id] )->all();
    $arr = array();
    foreach( $data as $data ) {       
        //do something
        $countChilds = models\Categories::find()->where( ['parent_id'=>$data->id] )->count();
        if( $countChilds > 0 ){
            $catData['sub_categories'] = $this->getElements( $parent_id = $data->id, $level + 1);
        }
        $arr[] = $catData;
    }
    return $arr;
}

在上面的代码中，我做了两处改动。

• 如果是$level == 3，则立即返回。无需将其放在 foreach 中。
• 它应该是 $catData['sub_categories'] = $this->getElements( $parent_id = $data->id, $level + 1); 而不是$level++，因为子级将有父级+ 1，而后递增运算符不会这样做。此外，即使 ++$level(pre-increment operation) 也不是一个好主意，因为即使对于 foreach 循环中下一个即将出现的条目，您也在修改变量。所以，$level + 1 是正确的方式。