Online PHP editor | refs for 6ULBZ

<?php $rows = [ [ 'id' => '1', 'file' => 'file_1_no_subfolder.doc', 'parent_id' => 0, ], [ 'id' => '2', 'file' => 'file_2_no_subfolder.doc', 'parent_id' => 0, ], [ 'id' => '3', 'file' => 'folder-1', 'parent_id' => 0, ], [ 'id' => '4', 'file' => 'folder-1_file_1.doc', 'parent_id' => 3, ], [ 'id' => '5', 'file' => 'folder-1_file_2.doc', 'parent_id' => 3, ], [ 'id' => '6', 'file' => 'folder-1_file_3.doc', 'parent_id' => 3, ], [ 'id' => '7', 'file' => 'folder-2', 'parent_id' => 0, ], [ 'id' => 8, 'file' => 'folder-2_file-1.doc', 'parent_id' => 7, ], [ 'id' => 9, 'file' => 'folder-2_file-1.doc', 'parent_id' => 7, ], [ 'id' => 10, 'file' => 'folder-2_file-1.doc', 'parent_id' => 7, ], ]; 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 );