ViewExecutable::render

public ViewExecutable::render($display_id = NULL)

public function render($display_id = NULL) {
  $this->execute($display_id);

  // Check to see if the build failed.
  if (!empty($this->build_info['fail'])) {
    return;
  }
  if (!empty($this->build_info['denied'])) {
    return;
  }

  /** @var \Drupal\views\Plugin\views\exposed_form\ExposedFormPluginInterface $exposed_form */
  $exposed_form = $this->display_handler->getPlugin('exposed_form');
  $exposed_form->preRender($this->result);

  $module_handler = \Drupal::moduleHandler();

  // @TODO In the longrun, it would be great to execute a view without
  //   the theme system at all. See https://www.drupal.org/node/2322623.
  $active_theme = \Drupal::theme()->getActiveTheme();
  $themes = array_keys($active_theme->getBaseThemes());
  $themes[] = $active_theme->getName();

  // Check for already-cached output.
  /** @var \Drupal\views\Plugin\views\cache\CachePluginBase $cache */
  if (!empty($this->live_preview)) {
    $cache = Views::pluginManager('cache')->createInstance('none');
  }
  else {
    $cache = $this->display_handler->getPlugin('cache');
  }

  // Run preRender for the pager as it might change the result.
  if (!empty($this->pager)) {
    $this->pager->preRender($this->result);
  }

  // Initialize the style plugin.
  $this->initStyle();

  if (!isset($this->response)) {
    // Set the response so other parts can alter it.
    $this->response = new Response('', 200);
  }

  // Give field handlers the opportunity to perform additional queries
  // using the entire resultset prior to rendering.
  if ($this->style_plugin->usesFields()) {
    foreach ($this->field as $id => $handler) {
      if (!empty($this->field[$id])) {
        $this->field[$id]->preRender($this->result);
      }
    }
  }

  $this->style_plugin->preRender($this->result);

  // Let each area handler have access to the result set.
  $areas = array('header', 'footer');
  // Only call preRender() on the empty handlers if the result is empty.
  if (empty($this->result)) {
    $areas[] = 'empty';
  }
  foreach ($areas as $area) {
    foreach ($this->{$area} as $handler) {
      $handler->preRender($this->result);
    }
  }

  // Let modules modify the view just prior to rendering it.
  $module_handler->invokeAll('views_pre_render', array($this));

  // Let the themes play too, because pre render is a very themey thing.
  foreach ($themes as $theme_name) {
    $function = $theme_name . '_views_pre_render';
    if (function_exists($function)) {
      $function($this);
    }
  }

  $this->display_handler->output = $this->display_handler->render();

  $exposed_form->postRender($this->display_handler->output);

  $cache->postRender($this->display_handler->output);

  // Let modules modify the view output after it is rendered.
  $module_handler->invokeAll('views_post_render', array($this, &$this->display_handler->output, $cache));

  // Let the themes play too, because post render is a very themey thing.
  foreach ($themes as $theme_name) {
    $function = $theme_name . '_views_post_render';
    if (function_exists($function)) {
      $function($this, $this->display_handler->output, $cache);
    }
  }

  return $this->display_handler->output;
}