Implementation of Recursive Classification Algorithm for php Menu and Comment Data

In the development process, we often encounter grading scenarios, such as menu grading, comments, commodity type grading and so on; It is possible to design a single table structure in the same mysql data table, as follows:

 $menuList = [
  [ 'id' => 1,'parent_id' => 0, 'name' => ' Node 1'],
  [ 'id' => 2,'parent_id' => 1, 'name' => ' Node 1-1'],
  [ 'id' => 3,'parent_id' => 0, 'name' => ' Node 2'],
  [ 'id' => 4,'parent_id' => 3, 'name' => ' Node 2-1'],
  [ 'id' => 5,'parent_id' => 2, 'name' => ' Node 1-1-1'],
  [ 'id' => 6,'parent_id' => 1, 'name' => ' Node 1-2'],
 ];

At this time, in the process of processing presentation, it is necessary to transform the above structure into a more intuitive data structure, such as:

$treeList = [
 [
 children: [
  children: []
 ]
 ]
 [,
 children: [
  children: []
 ]
 ]
];

The algorithm code is as follows:

<?php

class Menu
{
 /**
  *  Recursive loop menu list ,  Convert to menu tree 
  * @param $treeList  Menu tree list 
  * @param $menuList  Menu list 
  * @return bool
  */
 public function getMenuTree(&$treeList, $menuList)
 {
  //  Initialize the top-level parent node 
  if (! count($treeList)) {
   foreach($menuList as $index => $menu) {
    if ($menu['parent_id'] == 0) {
     $treeList[] = $menu;
     unset($menuList[$index]);
    }
   }
  }

  //  Recursive lookup of child nodes 
  foreach ($treeList as &$tree) {
   foreach ($menuList as $index => $menu) {
    if (empty($tree['children'])) {
     $tree['children'] = [];
    }
    if ($menu['parent_id'] == $tree['id']) {
     $tree['children'][] = $menu;
     unset($menuList[$index]);
    }
   }
   if (! empty($tree['children'])) {
    $this->getMenuTree($tree['children'], $menuList);
   } else {
    //  Recursive critical point 
    return false;
   }
  }
 }

}

$menuList = [
 [ 'id' => 1,'parent_id' => 0, 'name' => ' Node 1'],
 [ 'id' => 2,'parent_id' => 1, 'name' => ' Node 1-1'],
 [ 'id' => 3,'parent_id' => 0, 'name' => ' Node 2'],
 [ 'id' => 4,'parent_id' => 3, 'name' => ' Node 2-1'],
 [ 'id' => 5,'parent_id' => 2, 'name' => ' Node 1-1-1'],
 [ 'id' => 6,'parent_id' => 1, 'name' => ' Node 1-2'],
];
$treeList = [];
(new Menu)->getMenuTree($treeList, $menuList);
print_r($treeList);

happy coding!

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