Extend Views with plugins

Where handlers act on one column, plugins control the machinery of a view (a configuration-defined query plus display, built in the admin UI): the style lays out the whole result set, the row renders one result, the pager pages, access guards the display. This guide writes a style plugin that renders a field as a comma-separated list.

Goal

Add a new layout or behavior to the Views UI that any view can select. Reach for a style plugin when the built-in table, grid, and list layouts do not fit; for one-off markup, a Twig template override of an existing style is lighter.

Prerequisites

• A custom module, per Scaffold a module.
• The core Views module (installed by the standard profile).
• Plugins for the discovery system.

Write the style plugin

A style plugin extends StylePluginBase. Put it in src/Plugin/views/style/ and declare it with the #[ViewsStyle] attribute. Two protected properties decide its behavior: $usesRowPlugin (whether each row is rendered by a separate row plugin) and $usesFields (whether it works with the view’s fields).

web/modules/custom/howto_views/src/Plugin/views/style/CommaList.php

<?php

declare(strict_types=1);

namespace Drupal\howto_views\Plugin\views\style;

use Drupal\Core\StringTranslation\TranslatableMarkup;
use Drupal\views\Attribute\ViewsStyle;
use Drupal\views\Plugin\views\style\StylePluginBase;

/**
 * Renders a view's first field as a comma-separated list.
 *
 * A style plugin controls how the whole result set is laid out (a table,
 * a grid, a list). This one joins one field across all rows into a single
 * line, instead of one block per row.
 */
#[ViewsStyle(
  id: 'howto_comma_list',
  title: new TranslatableMarkup('Comma-separated list'),
  help: new TranslatableMarkup('Renders the first field of each row, joined by commas.'),
  display_types: ['normal'],
)]
final class CommaList extends StylePluginBase {

  /**
   * This style renders fields directly, without a per-row plugin.
   *
   * @var bool
   */
  protected $usesRowPlugin = FALSE;

  /**
   * This style operates on fields.
   *
   * @var bool
   */
  protected $usesFields = TRUE;

  /**
   * {@inheritdoc}
   */
  public function render(): array {
    $this->renderFields($this->view->result);
    $field_id = array_key_first($this->view->field);

    $items = [];
    foreach (array_keys($this->view->result) as $index) {
      $items[] = strip_tags((string) $this->getField($index, $field_id));
    }

    return ['#markup' => implode(', ', $items)];
  }

}

Because this style sets $usesRowPlugin = FALSE, it renders fields itself: renderFields() prepares them, and getField() returns each rendered value. A style that wraps rows in markup instead sets theme: on the attribute and ships a Twig template.

Verify

The example module ships a view that uses the style. After installing it:

ddev drush pm:install howto_views
ddev drush php:eval "
  \$v = \Drupal\views\Views::getView('howto_comma_titles');
  print \Drupal::service('renderer')->renderInIsolation(\$v->preview());
"

prints the node titles joined by commas. The module’s kernel test renders the view and asserts the comma-joined output.

Variations

Other plugin families

Each Views plugin family has its own base class, directory, and attribute:

Plugin	Base class	Directory	Attribute
Style	StylePluginBase	src/Plugin/views/style	ViewsStyle
Row	RowPluginBase	src/Plugin/views/row	ViewsRow
Pager	PagerPluginBase	src/Plugin/views/pager	ViewsPager
Access	AccessPluginBase	src/Plugin/views/access	ViewsAccess
Argument default	ArgumentDefaultPluginBase	src/Plugin/views/argument_default	ViewsArgumentDefault

An access plugin returns whether the current user may see a display; an argument-default plugin supplies a contextual filter value (the current user, a node from the route) when none is in the URL.

Related

• Extend Views with handlers for field, filter, sort, and argument handlers.
• Plugins for the discovery system.
• The Views plugins topic on api.drupal.org.