MachineName.php

<?php

namespace Drupal\views\Plugin\views\field;

use Drupal\Core\Form\FormStateInterface;
use Drupal\views\Attribute\ViewsField;
use Drupal\views\ResultRow;

/**
 * Field handler which allows to show machine name content as human name.
 * @ingroup views_field_handlers
 *
 * Definition items:
 * - options callback: The function to call in order to generate the value options. If omitted, the options 'Yes' and 'No' will be used.
 * - options arguments: An array of arguments to pass to the options callback.
 */
class MachineName extends FieldPluginBase {
    
    /**
     * Stores the available options.
     *
     * @var array
     */
    protected $valueOptions;
    public function getValueOptions() {
        if (isset($this->valueOptions)) {
            return;
        }
        if (isset($this->definition['options callback']) && is_callable($this->definition['options callback'])) {
            if (isset($this->definition['options arguments']) && is_array($this->definition['options arguments'])) {
                $this->valueOptions = call_user_func_array($this->definition['options callback'], $this->definition['options arguments']);
            }
            else {
                $this->valueOptions = call_user_func($this->definition['options callback']);
            }
        }
        else {
            $this->valueOptions = [];
        }
    }
    
    /**
     * {@inheritdoc}
     */
    protected function defineOptions() {
        $options = parent::defineOptions();
        $options['machine_name'] = [
            'default' => FALSE,
        ];
        return $options;
    }
    
    /**
     * {@inheritdoc}
     */
    public function buildOptionsForm(&$form, FormStateInterface $form_state) {
        parent::buildOptionsForm($form, $form_state);
        $form['machine_name'] = [
            '#title' => $this->t('Output machine name'),
            '#description' => $this->t('Display field as machine name.'),
            '#type' => 'checkbox',
            '#default_value' => !empty($this->options['machine_name']),
        ];
    }
    
    /**
     * {@inheritdoc}
     */
    public function preRender(&$values) {
        $this->getValueOptions();
    }
    
    /**
     * {@inheritdoc}
     */
    public function render(ResultRow $values) {
        $value = $values->{$this->field_alias};
        if (!empty($this->options['machine_name']) || !isset($this->valueOptions[$value])) {
            $result = $this->sanitizeValue($value);
        }
        else {
            $result = $this->valueOptions[$value];
        }
        return $result;
    }

}