class NodeTermData

class NodeTermData extends RelationshipPluginBase {
    
    /**
     * The vocabulary storage.
     *
     * @var \Drupal\taxonomy\VocabularyStorageInterface
     */
    protected $vocabularyStorage;
    
    /**
     * Constructs a NodeTermData object.
     *
     * @param array $configuration
     *   A configuration array containing information about the plugin instance.
     * @param string $plugin_id
     *   The plugin_id for the plugin instance.
     * @param mixed $plugin_definition
     *   The plugin implementation definition.
     * @param \Drupal\taxonomy\VocabularyStorageInterface $vocabulary_storage
     *   The vocabulary storage.
     */
    public function __construct(array $configuration, $plugin_id, $plugin_definition, VocabularyStorageInterface $vocabulary_storage) {
        parent::__construct($configuration, $plugin_id, $plugin_definition);
        $this->vocabularyStorage = $vocabulary_storage;
    }
    
    /**
     * {@inheritdoc}
     */
    public static function create(ContainerInterface $container, array $configuration, $plugin_id, $plugin_definition) {
        return new static($configuration, $plugin_id, $plugin_definition, $container->get('entity_type.manager')
            ->getStorage('taxonomy_vocabulary'));
    }
    protected function defineOptions() {
        $options = parent::defineOptions();
        $options['vids'] = [
            'default' => [],
        ];
        return $options;
    }
    public function buildOptionsForm(&$form, FormStateInterface $form_state) {
        $vocabularies = $this->vocabularyStorage
            ->loadMultiple();
        $options = [];
        foreach ($vocabularies as $voc) {
            $options[$voc->id()] = $voc->label();
        }
        $form['vids'] = [
            '#type' => 'checkboxes',
            '#title' => $this->t('Vocabularies'),
            '#options' => $options,
            '#default_value' => $this->options['vids'],
            '#description' => $this->t('Choose which vocabularies you wish to relate. Remember that every term found will create a new record, so this relationship is best used on just one vocabulary that has only one term per node.'),
        ];
        parent::buildOptionsForm($form, $form_state);
    }
    
    /**
     * {@inheritdoc}
     */
    public function submitOptionsForm(&$form, FormStateInterface $form_state) {
        // Transform the #type = checkboxes value to a numerically indexed array,
        // because the config schema expects a sequence, not a mapping.
        $vids = $form_state->getValue([
            'options',
            'vids',
        ]);
        $form_state->setValue([
            'options',
            'vids',
        ], array_values(array_filter($vids)));
    }
    
    /**
     * Called to implement a relationship in a query.
     */
    public function query() {
        $this->ensureMyTable();
        $def = $this->definition;
        $def['table'] = 'taxonomy_term_field_data';
        if (!array_filter($this->options['vids'])) {
            $taxonomy_index = $this->query
                ->addTable('taxonomy_index', $this->relationship);
            $def['left_table'] = $taxonomy_index;
            $def['left_field'] = 'tid';
            $def['field'] = 'tid';
            $def['type'] = empty($this->options['required']) ? 'LEFT' : 'INNER';
        }
        else {
            // If vocabularies are supplied join a subselect instead
            $def['left_table'] = $this->tableAlias;
            $def['left_field'] = 'nid';
            $def['field'] = 'nid';
            $def['type'] = empty($this->options['required']) ? 'LEFT' : 'INNER';
            $def['adjusted'] = TRUE;
            $query = Database::getConnection()->select('taxonomy_term_field_data', 'td');
            $query->addJoin($def['type'], 'taxonomy_index', 'tn', '[tn].[tid] = [td].[tid]');
            $query->condition('td.vid', array_filter($this->options['vids']), 'IN');
            if (empty($this->query->options['disable_sql_rewrite'])) {
                $query->addTag('taxonomy_term_access');
            }
            $query->fields('td');
            $query->fields('tn', [
                'nid',
            ]);
            $def['table formula'] = $query;
        }
        $join = \Drupal::service('plugin.manager.views.join')->createInstance('standard', $def);
        // use a short alias for this:
        $alias = $def['table'] . '_' . $this->table;
        $this->alias = $this->query
            ->addRelationship($alias, $join, 'taxonomy_term_field_data', $this->relationship);
    }
    
    /**
     * {@inheritdoc}
     */
    public function calculateDependencies() {
        $dependencies = parent::calculateDependencies();
        foreach ($this->options['vids'] as $vocabulary_id) {
            if ($vocabulary = $this->vocabularyStorage
                ->load($vocabulary_id)) {
                $dependencies[$vocabulary->getConfigDependencyKey()][] = $vocabulary->getConfigDependencyName();
            }
        }
        return $dependencies;
    }

}