eck-8.x-1.x-dev/src/Plugin/views/field/EckEntityLabel.php

<?php

namespace Drupal\eck\Plugin\views\field;

use Drupal\Core\Entity\EntityMalformedException;
use Drupal\Core\Entity\Exception\UndefinedLinkTemplateException;
use Drupal\Core\Form\FormStateInterface;
use Drupal\views\Plugin\views\field\FieldPluginBase;
use Drupal\views\ResultRow;

/**
 * Field handler to return the ECK entity's label.
 *
 * @ingroup views_field_handlers
 *
 * @ViewsField("eck_entity_label")
 */
class EckEntityLabel extends FieldPluginBase {

  /**
   * {@inheritdoc}
   */
  protected function defineOptions() {
    $options = parent::defineOptions();
    $options['link_to_entity'] = ['default' => FALSE];
    return $options;
  }

  /**
   * {@inheritdoc}
   */
  public function buildOptionsForm(&$form, FormStateInterface $form_state) {
    $form['link_to_entity'] = [
      '#title' => $this->t('Link to entity'),
      '#description' => $this->t('Make entity label a link to entity page.'),
      '#type' => 'checkbox',
      '#default_value' => !empty($this->options['link_to_entity']),
    ];
    parent::buildOptionsForm($form, $form_state);
  }

  /**
   * {@inheritdoc}
   */
  public function render(ResultRow $values) {
    /** @var \Drupal\Core\Entity\EntityInterface $entity */
    $entity = $values->_entity;

    if (!empty($this->options['link_to_entity'])) {
      try {
        $this->options['alter']['url'] = $entity->toUrl();
        $this->options['alter']['make_link'] = TRUE;
      }
      catch (UndefinedLinkTemplateException $e) {
        $this->options['alter']['make_link'] = FALSE;
      }
      catch (EntityMalformedException $e) {
        $this->options['alter']['make_link'] = FALSE;
      }
    }

    return $entity->label();
  }

  /**
   * {@inheritdoc}
   */
  public function query() {
    // Leave empty to avoid a query on this field.
  }

}