TermName.php

<?php

namespace Drupal\taxonomy\Plugin\views\argument_validator;

use Drupal\Core\Entity\EntityTypeBundleInfoInterface;
use Drupal\Core\Entity\EntityTypeManagerInterface;
use Drupal\Core\Form\FormStateInterface;
use Drupal\views\Plugin\views\argument_validator\Entity;

/**
 * Validates whether a term name is a valid term argument.
 *
 * @ViewsArgumentValidator(
 *   id = "taxonomy_term_name",
 *   title = @Translation("Taxonomy term name"),
 *   entity_type = "taxonomy_term"
 * )
 */
class TermName extends Entity {
    
    /**
     * The taxonomy term storage.
     *
     * @var \Drupal\taxonomy\TermStorageInterface
     */
    protected $termStorage;
    
    /**
     * {@inheritdoc}
     */
    public function __construct(array $configuration, $plugin_id, $plugin_definition, EntityTypeManagerInterface $entity_type_manager, EntityTypeBundleInfoInterface $entity_type_bundle_info = NULL) {
        parent::__construct($configuration, $plugin_id, $plugin_definition, $entity_type_manager, $entity_type_bundle_info);
        // Not handling exploding term names.
        $this->multipleCapable = FALSE;
        $this->termStorage = $entity_type_manager->getStorage('taxonomy_term');
    }
    
    /**
     * {@inheritdoc}
     */
    protected function defineOptions() {
        $options = parent::defineOptions();
        $options['transform'] = [
            'default' => FALSE,
        ];
        return $options;
    }
    
    /**
     * {@inheritdoc}
     */
    public function buildOptionsForm(&$form, FormStateInterface $form_state) {
        parent::buildOptionsForm($form, $form_state);
        $form['transform'] = [
            '#type' => 'checkbox',
            '#title' => $this->t('Transform dashes in URL to spaces in term name filter values'),
            '#default_value' => $this->options['transform'],
        ];
    }
    
    /**
     * {@inheritdoc}
     */
    public function validateArgument($argument) {
        if ($this->options['transform']) {
            $argument = str_replace('-', ' ', $argument);
            $this->argument->argument = $argument;
        }
        $terms = $this->termStorage
            ->loadByProperties([
            'name' => $argument,
        ]);
        if (!$terms) {
            // Returned empty array no terms with the name.
            return FALSE;
        }
        // Not knowing which term will be used if more than one is returned check
        // each one.
        foreach ($terms as $term) {
            if (!$this->validateEntity($term)) {
                return FALSE;
            }
        }
        return TRUE;
    }

}