Hi, Danny,
Thanks for this effort to solve a common problem
Would you post an example of using this class?
Is it $tree = TaxonomyTermTree::load( 'machine_name' );

I am getting error:
Fatal error: Call to a member function getStorage() on null in ....../modules/contrib/taxonomy_tree/src/TaxonomyTermTree.php on line 35

thanks

Thanks, Danny for your quick response.

This really doesn't help me however. I am not finding documentation on the use of EntityTypeManager() and I obviously don't know how to use it.
I am trying
$etm = new EntityTypeManager( 'taxonomy' );
$tt = new TaxonomyTermTree( $etm );;
$tree = TaxonomyTermTree::load( 'machine_name' );

and get Error: Argument 1 passed to Drupal\Core\Entity\EntityTypeManager::__construct() must implement interface Traversable,

Would you be able to provide an example using your TaxonomyTermTree?

Thanks again.

Usage example

$tt = \Drupal::service('taxonomy_tree.taxonomy_term_tree');     
 $tree = $tt->load('services');

You can actually load entity with loadTree. You just need to set last parameter to TRUE. This may help you as a shortcut in your function..

https://api.drupal.org/api/drupal/core%21modules%21taxonomy%21src%21TermStorage.php/function/TermStorage%3A%3AloadTree/8.2.x

$vocabulary_entities = \Drupal::entityTypeManager()->getStorage('taxonomy_term')->loadTree('vocablary_id', 0, NULL, TRUE);

I'm hoping this solution solves my need to show a select field with hierarchy on the content adding page, using a custom widget. But implementing this, seems to be above my skill level. I installed the module, and tried to do it like this:

    $tt = Drupal::service('taxonomy_tree.taxonomy_term_tree');
    $tree = $tt->load('plant_part');

$element['plant_part_described'] = array(
        '#type' => 'select',
        '#options' => $tree,
        '#title' => t('title'),
        '#size' => 1,       
        '#default_value' => isset($items[$delta]->plant_part_described) ? $items[$delta]->plant_part_described : NULL,
    );

I also tried adding at the top of the file: use Drupal\taxonomy_tree;

Maybe I just don't know how to include services...

Suggestions?

Hi I just install this plugin and want to acsses the tree in a variable so i just write this code in module file
function taxonomy_tree_preprocess_page(&$variables) {
$tt = \Drupal::service('taxonomy_tree.taxonomy_term_tree');
$trr = load('file_folders');
kint($trr);
die('here');
}
i got error Error: Call to undefined function load() in taxonomy_tree_preprocess_page() (line 21 of modules\taxonomy_tree-master\taxonomy_tree.module).
plez suggest

Using cs's code as example this could be implemented like this:

$tt = Drupal::service('taxonomy_tree.taxonomy_term_tree');
$tree = $tt->load('plant_part');

$tags_tree = [];
foreach ($tree as $tree_item) {
  $tags_tree[$tree_item->tid] = $tree_item->name;
  if(!empty($tree_item->children)){
    foreach ($tree_item->children as $child_item){
      //add space and two dashes before child items
      $tags_tree[$child_item->tid] = ' -- ' . $child_item->name;
    }
  }
}

$element['plant_part_described'] = array(
  '#type' => 'select',
  '#options' => $tags_tree,
  '#title' => t('title'),
  '#size' => 1,
  '#default_value' => isset($items[$delta]->plant_part_described) ? $items[$delta]->plant_part_described : NULL,
  '#required' => TRUE,
);

Hi, cool code, I have got the ordering working like this

<?php

namespace Drupal\taxonomy_tree;

use Drupal\Component\Plugin\Exception\InvalidPluginDefinitionException;
use Drupal\Component\Plugin\Exception\PluginNotFoundException;
use Drupal\Core\Entity\EntityTypeManager;

/**
 * Loads taxonomy terms in a tree
 */
class TaxonomyTermTree
{

    /**
     * @var EntityTypeManager
     */
    protected $entityTypeManager;

    /**
     * TaxonomyTermTree constructor.
     *
     * @param EntityTypeManager $entityTypeManager
     */
    public function __construct(EntityTypeManager $entityTypeManager)
    {
        $this->entityTypeManager = $entityTypeManager;
    }

    /**
     * Loads the tree of a vocabulary.
     *
     * @param $vocabulary
     * @return array
     * @throws InvalidPluginDefinitionException
     * @throws PluginNotFoundException
     */
    public function load($vocabulary): array
    {
        $terms = $this->entityTypeManager->getStorage('taxonomy_term')->loadTree($vocabulary);
        $tree = [];
        foreach ($terms as $tree_object) {
            $this->buildTree($tree, $tree_object, $vocabulary);
        }

        return $tree;
    }

    /**
     * Populates a tree array given a taxonomy term tree object.
     *
     * @param $tree
     * @param $object
     * @param $vocabulary
     * @throws InvalidPluginDefinitionException
     * @throws PluginNotFoundException
     */
    protected function buildTree(&$tree, $object, $vocabulary): void
    {
        if ($object->depth != 0) {
            return;
        }
        $key = 'tid_' . $object->tid;

        $tree[$key] = $object;
        $tree[$key]->children = [];
        $object_children = &$tree[$key]->children;

        $children = $this->entityTypeManager->getStorage('taxonomy_term')->loadChildren($object->tid);
        if (!$children) {
            return;
        }

        $child_tree_objects = $this->entityTypeManager->getStorage('taxonomy_term')->loadTree($vocabulary, $object->tid);

        foreach ($children as $child) {
            foreach ($child_tree_objects as $child_tree_object) {
                if ($child_tree_object->tid == $child->id()) {
                    $this->buildTree($object_children, $child_tree_object, $vocabulary);
                }
            }
        }

        uasort($tree, function ($a, $b) {
            return $a->weight <=> $b->weight;
        });
        uasort($object_children, function ($a, $b) {
            return $a->weight <=> $b->weight;
        });
    }
}

I can't understand how these references works

$object_children = &$tree[$object->tid]->children;

and then

foreach ($children as $child) {
      foreach ($child_tree_objects as $child_tree_object) {
        if ($child_tree_object->tid == $child->id()) {
         $this->buildTree($object_children, $child_tree_object, $vocabulary);
        }
      }
    }

Hey Daniel, I have managed to make a more simpler service to get terms as a nested array.

It returns an array of taxonomy terms, with each term having an extra children property, which is an array of terms again having a children property.

/**
 * Class TaxonomyUtils
 */
class TaxonomyUtils {
  
  /**
   * @var \Drupal\taxonomy\TermStorage
   */
  protected $taxonomyStorage;

  public function __construct(EntityTypeManagerInterface $entityTypeManager) {
    $this->taxonomyStorage = $entityTypeManager->getStorage('taxonomy_term');
  }

  /**
   * @param string $vocabulary
   * @param int $parent
   *
   * @return array
   */
  public function getTree(string $vocabulary, int $parent = 0) {
    $terms = $this->taxonomyStorage->loadTree($vocabulary, $parent, 1, TRUE);
    $tree = [];

    foreach ($terms as $term) {
      $term->children = $this->getTree($vocabulary, $term->id());
      $tree[$term->id()] = $term;
    }

    return $tree;
  }

}

my_module.services.yml

services:
  my_module.taxonomy_utils:
    class: Drupal\my_module\Utils\TaxonomyUtils
    arguments: [ '@entity_type.manager' ]

Hi,
I am looking for a solution like this in Drupal 10.
To add terms on node pages, with treir lineage attached.

So for instance, I have a node related to a place in Amsterdam.
I would like to be able to add the following terms as regional information:

• Holland
  ---North Holland
  -----Amsterdam.

And with another node, for example in Rotterdam, add only:
---South Holland
-----Rotterdam

Can youi help me with this?
Greetings, Summit on drupal.org, Martijn