Online PHP editor | output for L2jiM

<?php $rows = [ ['id' => 1, 'parent_id' => 0, 'name' => 'parent'], ['id' => 2, 'parent_id' => 1, 'name' => 'child'], ['id' => 3, 'parent_id' => 2, 'name' => 'grandchild'], ['id' => 4, 'parent_id' => 0, 'name' => 'parent 2'], ['id' => 5, 'parent_id' => 4, 'name' => 'child 2'], ['id' => 6, 'parent_id' => 1, 'name' => 'child'], ]; function buildTree(array $elements, $parentId = 0) { $branch = array(); foreach ($elements as $element) { if ($element['parent_id'] == $parentId) { $children = buildTree($elements, $element['id']); if ($children) { $element['children'] = $children; } $branch[] = $element; } } return $branch; } $tree = buildTree($rows); print_r($tree);