getVocabularyHierarchyType example

  public function buildForm(array $form, FormStateInterface $form_state, VocabularyInterface $taxonomy_vocabulary = NULL) {
    $form_state->set(['taxonomy', 'vocabulary'], $taxonomy_vocabulary);
    $vocabulary_hierarchy = $this->storageController->getVocabularyHierarchyType($taxonomy_vocabulary->id());
    $parent_fields = FALSE;

    $page = $this->pagerManager->findPage();
    // Number of terms per page.     $page_increment = $this->config('taxonomy.settings')->get('terms_per_page_admin');
    // Elements shown on this page.     $page_entries = 0;
    // Elements at the root level before this page.     $before_entries = 0;
    // Elements at the root level after this page.     $after_entries = 0;
    

/** @var \Drupal\taxonomy\TermStorageInterface $taxonomy_storage */
    $taxonomy_storage = $this->entityTypeManager->getStorage('taxonomy_term');
    $vocabulary = $vocab_storage->load($term->bundle());

    $parent = $this->getParentIds($term);
    $form_state->set(['taxonomy', 'parent'], $parent);
    $form_state->set(['taxonomy', 'vocabulary'], $vocabulary);

    $form['relations'] = [
      '#type' => 'details',
      '#title' => $this->t('Relations'),
      '#open' => $taxonomy_storage->getVocabularyHierarchyType($vocabulary->id()) == VocabularyInterface::HIERARCHY_MULTIPLE,
      '#weight' => 10,
    ];

    // \Drupal\taxonomy\TermStorageInterface::loadTree() and     // \Drupal\taxonomy\TermStorageInterface::loadParents() may contain large     // numbers of items so we check for taxonomy.settings:override_selector     // before loading the full vocabulary. Contrib modules can then intercept     // before hook_form_alter to provide scalable alternatives.     if (!$this->config('taxonomy.settings')->get('override_selector')) {
      $exclude = [];
      if (!$term->isNew()) {
        

  public function testTaxonomyTermHierarchy() {
    // Create two taxonomy terms.     $term1 = $this->createTerm($this->vocabulary);
    $term2 = $this->createTerm($this->vocabulary);

    // Get the taxonomy storage.     /** @var \Drupal\taxonomy\TermStorageInterface $taxonomy_storage */
    $taxonomy_storage = $this->container->get('entity_type.manager')->getStorage('taxonomy_term');

    // Check that hierarchy is flat.     $this->assertEquals(0, $taxonomy_storage->getVocabularyHierarchyType($this->vocabulary->id()), 'Vocabulary is flat.');

    // Edit $term2, setting $term1 as parent.     $edit = [];
    $edit['parent[]'] = [$term1->id()];
    $this->drupalGet('taxonomy/term/' . $term2->id() . '/edit');
    $this->submitForm($edit, 'Save');

    // Check the hierarchy.     $children = $taxonomy_storage->loadChildren($term1->id());
    $parents = $taxonomy_storage->loadParents($term2->id());
    $this->assertTrue(isset($children[$term2->id()]), 'Child found correctly.');