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<?php $menu = [ 0 => [ 'id' => 1, 'parent_id' => 0, 'title' => 'Category 1', ], 2 => [ 'id' => 2, 'parent_id' => 0, 'title' => 'Category 2', ], 3 => [ 'id' => 3, 'parent_id' => 2, 'title' => 'Category 3', ], 4 => [ 'id' => 4, 'parent_id' => 3, 'title' => 'Category 4', ] ]; function appendItem(array &$haystack, array $toAppend): void { foreach ($haystack as &$menuItem) { if ($menuItem['id'] === $toAppend['parent_id']) { if (array_key_exists('child', $menuItem)) { $menuItem['child'][] = $toAppend; } else { $menuItem['child'] = [$toAppend]; } return; } if (array_key_exists('child', $menuItem)) { appendItem($menuItem['child'], $toAppend); } } } foreach ($menu as $key => $menuItem) { if ($menuItem['parent_id'] !== 0) { unset($menu[$key]); appendItem($menu, $menuItem); } } var_dump($menu);
Output for 7.3.0 - 7.3.33, 7.4.0 - 7.4.33, 8.0.0 - 8.0.30, 8.1.0 - 8.1.34, 8.2.0 - 8.2.30, 8.3.0 - 8.3.4, 8.3.6 - 8.3.30, 8.4.1 - 8.4.18, 8.5.0 - 8.5.3
array(2) { [0]=> array(3) { ["id"]=> int(1) ["parent_id"]=> int(0) ["title"]=> string(10) "Category 1" } [2]=> array(4) { ["id"]=> int(2) ["parent_id"]=> int(0) ["title"]=> string(10) "Category 2" ["child"]=> array(1) { [0]=> array(4) { ["id"]=> int(3) ["parent_id"]=> int(2) ["title"]=> string(10) "Category 3" ["child"]=> array(1) { [0]=> array(3) { ["id"]=> int(4) ["parent_id"]=> int(3) ["title"]=> string(10) "Category 4" } } } } } }
Output for 8.3.5
Warning: PHP Startup: Unable to load dynamic library 'sodium.so' (tried: /usr/lib/php/8.3.5/modules/sodium.so (libsodium.so.23: cannot open shared object file: No such file or directory), /usr/lib/php/8.3.5/modules/sodium.so.so (/usr/lib/php/8.3.5/modules/sodium.so.so: cannot open shared object file: No such file or directory)) in Unknown on line 0 array(2) { [0]=> array(3) { ["id"]=> int(1) ["parent_id"]=> int(0) ["title"]=> string(10) "Category 1" } [2]=> array(4) { ["id"]=> int(2) ["parent_id"]=> int(0) ["title"]=> string(10) "Category 2" ["child"]=> array(1) { [0]=> array(4) { ["id"]=> int(3) ["parent_id"]=> int(2) ["title"]=> string(10) "Category 3" ["child"]=> array(1) { [0]=> array(3) { ["id"]=> int(4) ["parent_id"]=> int(3) ["title"]=> string(10) "Category 4" } } } } } }

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