How to turn a menu tree into an associative array?

Question

I've dig into Drupal menu core to find out a way to build an associative array from a menu tree(eg,the account menu) so that I can output the data as json format. But it seems not possible to do this with Drupal 8. The info I need from a menu tree include title, description, url, and I also need to know whether it has sub menu and if it's enabled. All this can be easily achieved using menu_build_tree() function in Drupal 7. Please understand I tried the so-called Drupal 8 equivalent of menu_build_tree() (\Drupal::menuTree();) but it just gives me large object using which I don't know how to extract the data I need.

Answer 1

You can load up the menu tree with MenuLinkTree::load, which will give you an array of menu links to work with. From there it's just a matter of looping through and getting what you need, e.g.

$tree = \Drupal::menuTree()->load('main', new \Drupal\Core\Menu\MenuTreeParameters());
foreach ($tree as $item) {
  $title = $item->link->getTitle();
  $url_obj = $item->link->getUrlObject();
  $has_children = $item->hasChildren;
  // etc...
}

The link is a MenuLinkInterface, each item itself is a MenuLinkTreeElement.

It would be preferable to inject the menu.link_tree service if possible, rather than getting it from \Drupal.

Answer 2

I'm quite late, but maybe helps someone looking for answers, here's my solution for generating recursive array from menu items.

private function generateSubMenuTree(&$output, &$input, $parent = FALSE) {
$input = array_values($input);
foreach($input as $key => $item) {
  //If menu element disabled skip this branch
  if ($item->link->isEnabled()) {
    $key = 'submenu-' . $key;
    $name = $item->link->getTitle();
    $url = $item->link->getUrlObject();
    $url_string = $url->toString();

    //If not root element, add as child
    if ($parent === FALSE) {
      $output[$key] = [
        'name' => $name,
        'tid' => $key,
        'url_str' => $url_string
      ];
    } else {
      $parent = 'submenu-' . $parent;
      $output['child'][$key] = [
        'name' => $name,
        'tid' => $key,
        'url_str' => $url_string
      ];
    }

    if ($item->hasChildren) {
      if ($item->depth == 1) {
        $this->generateSubMenuTree($output[$key], $item->subtree, $key);
      } else {
        $this->generateSubMenuTree($output['child'][$key], $item->subtree, $key);
      }
    }
  }
}

And call that function with

//Get drupal menu
$sub_nav = \Drupal::menuTree()->load('sub-navigation', new \Drupal\Core\Menu\MenuTreeParameters());
//Generate array
$this->generateSubMenuTree($menu_tree2, $sub_nav);