PHP分层数组 - 父母和孩子

Question

我正在创建一个父子层次结构数组。请在数组下方找到并帮助我修复。它parent_id在按顺序时工作正常，但我想保持我的数组值相同。function Testing(){    $tasks[] = array("id" => 1, "parent_id" => 0);    $tasks[] = array("id" => 2, "parent_id" => 5);    $tasks[] = array("id" => 3, "parent_id" => 2);    $tasks[] = array("id" => 5, "parent_id" => 3);    $tasks[] = array("id" => 4, "parent_id" => 3);    $tasks[] = array("id" => 6, "parent_id" => 5);    $tasks[] = array("id" => 7, "parent_id" => 6);    $tree = buildTree($tasks);    print("<pre>");print_r($tree);}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;}

Answer 1

为了避免无限循环的错误，当某些元素的子元素具有 parent_id 时，您可以使用第三个参数来列出所有已管理的 id。如果一个 id 在你的治疗中回来，你可以抛出一个异常：

function buildTree(array $elements, $parentId = 0, $managedParent = []) {

    $branch = array();

    // Add new id in list of managed ids

    $managedParent[] =$parentId;

    foreach ($elements as $element) {

        if ($element['parent_id'] == $parentId) {

          // check id not already managed

          if(in_array($element['id'], $managedParent))

          {

            // in this case children are already a parent of same structure. Throw an Excpetion

            throw new \Exception('Invalid structure given');

          }

          $children = buildTree($elements, $element['id'], $managedParent);

          if ($children) {

              $element['children'] = $children;

          }

          $branch[] = $element;

        }

    }

    return $branch;

}