views_details.module

<?php

/**
 * @file
 * Views details style plugin code.
 */

use Drupal\Core\Render\Element\RenderElement;
use Drupal\Core\Form\FormState;

/**
 * Implements hook_preprocess_HOOK() for theme_views_view_details().
 */
function template_preprocess_views_view_details(&$variables) {
  /** @var \Drupal\views\ViewExecutable $view */
  $view = $variables['view'];
  $rows = $variables['rows'];
  $style = $view->style_plugin;
  $options = $style->options;

  $default_row_class = isset($options['default_row_class']) ? $options['default_row_class'] : FALSE;
  foreach ($rows as $id => $row) {
    $classes = array();
    if ($default_row_class) {
      $classes[] = 'views-row';
    }

    if ($row_class = $view->style_plugin->getRowClass($id)) {
      $classes[] = $row_class;
    }

    $field = $options['title'];
    $title = '';
    if (isset($view->field[$field])) {
      $title = $style->getField($id, $field);
      if ($view->field[$field]->options['label']) {
        $title = $view->field[$field]->options['label'] . ': ' . $title;
      }
      $title = strip_tags(htmlspecialchars_decode($title));
    }
    $field = $options['description'];
    $description = '';
    if (isset($view->field[$field])) {
      $description = $style->getField($id, $field);
      if ($view->field[$field]->options['label']) {
        $description = $view->field[$field]->options['label'] . ': ' . $description;
      }
      $description = strip_tags(htmlspecialchars_decode($description));
    }

    $element = array(
      '#title' => $title,
      '#type' => 'details',
      '#open' => !$options['collapsed'],
      '#children' => $row,
      '#parents' => array(),
      '#description' => $description,
      '#attributes' => array(
        'class' => $classes,
      ),
    );
    // Leave first details open if all the details are collapsed and open
    // first is TRUE.
    if ($id == 0 && $options['collapsed'] && $options['open_first']) {
      $element['#open'] = TRUE;
    }
    $form = array();
    $form_state = new FormState();
    $element = RenderElement::processGroup($element, $form_state, $form);

    $variables['details'][] = $element;
  }

}