Drupal → Drupal 8 Dev FAQ

$ composer create-project drupal/recommended-project

$ composer create-project drupal/legacy-project

php -r "copy('https://getcomposer.org/installer', 'composer-setup.php');"
php composer-setup.php
php -r "unlink('composer-setup.php');"

php composer.phar require drupal/devel

$ composer update drupal/core* --with-all-dependencies
$ vendor/bin/drush updb

$ composer require drush/drush

$ composer require drupal/devel

$ composer require drupal/field_group:^3.0-rc2

$ composer require drupal/devel:1.x-dev

$ composer update drupal/devel --with-all-dependencies

$ composer update drupal/commerce* --with-all-dependencies

$ composer require drupal/devel:^3.0

$ composer require drupal/devel:4.x-dev

$ composer prohibits drupal/core 8.8.1

$ composer outdated

$ composer why symfony/process

$ composer show --all drupal/devel

$ vendor/bin/drush generate module

// По имени роута
$link = \Drupal\Core\Link::createFromRoute('My link', 'entity.node.canonical', ['node' => 123]);
 
// По пути
$url = \Drupal\Core\Url::fromUri('base:path/to/target');
$link = \Drupal\Core\Link::fromTextAndUrl('My link', $url);
 
// С помощью рендер-массива
$build = [
  '#type' => 'link',
  '#title' => 'Link text',
  '#url' => Url::fromRoute('<current>'),
];

$link = Link::fromTextAndUrl('Example', Url::fromUri('internal:#anchor'));

// src/Controller/ModulenameController.php
 
namespace Drupal\modulename\Controller;
 
use Drupal\Core\Controller\ControllerBase;
 
class ModulenameController extends ControllerBase {
  public function helloWorld() {
    return [
      '#markup' => 'Hello, World!',
    ];
  }
}

# modulename.routing.yml
 
modulename.hello_world:
  path: '/hello/world'
  defaults:
    _controller: '\Drupal\modulename\Controller\ModulenameController::helloWorld'
    _title: 'Hello, World!'
  requirements:
    _permission: 'access content'

$ vendor/bin/drush generate controller

// src/Plugin/Block/HelloWorldBlock.php
 
namespace Drupal\modulename\Plugin\Block;
 
use Drupal\Core\Block\BlockBase;
 
/**
 * @Block(
 *   id = "hello_world_block",
 *   admin_label = @Translation("Hello world block"),
 * )
 */
class HelloWorldBlock extends BlockBase {
  public function build() {
    return [
      '#title' => 'It\'s block title', // Optional
      '#markup' => 'Hello, World!',
    ];
  }
}

$ vendor/bin/drush generate block

use Drupal\Core\Cache\UncacheableDependencyTrait;
 
/**
 * @Block(...)
 */
class MyBlock extends BlockBase {
 
  use UncacheableDependencyTrait; // <---
 
  public function build() {
    ...
  }
 
}

/**
 * @Block(...)
 */
class MyBlock extends BlockBase {
 
  public function build() {
    ...
  }
 
  public function getCacheMaxAge() {
    return 0; // <---
  }
 
}

class MyBlock extends BlockBase {
 
  ...
 
  /**
   * {@inheritdoc}
   */
  public function access(AccountInterface $account, $return_as_object = FALSE) {
    $access = FALSE;
 
    if (...) {
      $access = TRUE;
    }
 
    return $return_as_object ? AccessResult::allowedIf($access) : $access;
  }
 
}

$site_mail = \Drupal::config('system.site')->get('mail');

$site_config = \Drupal::config('system.site');
 
$site_name = $site_config->get('name');
$site_slogan = $site_config->get('slogan');
$site_mail = $site_config->get('mail');

$ vendor/bin/drush cache-rebuild

drupal_flush_all_caches();

// Для отступов используется два пробела
function example() {
  $foo = 'bar';
}
 
// Между бинарными операторами ставится пробел
$a = 1 + 2; // Good
$a=1+2; // Bad
 
// Блок elseif/else начинается с новой строки
if (...) {
  ...
}
elseif (...) {
  ...
}
else {
  ...
}
 
// Массивы создаются с помощью короткого синтаксиса
$array = ['foo', 'bar']; // Good
$array = array('foo', 'bar'); // Bad
 
// Строки заключаются в одиночные кавычки
$string = 'foo'; // Good
$string = "foo"; // Bad
 
// Переменные именуются с помощью нижнего подчёркивания
$my_variable = 'foo'; // Good
$myVariable = 'foo'; // Bad
 
// Названия классов именуются в CamelCase
class MyFirstClass { }
 
// Переменные класса именуются в camelCase
class MyFirstClass {
  public $myFirstVariable;
}

\Drupal::messenger()->addMessage('Hello World!');

use Drupal\Component\Utility\Timer;
 
Timer::start('test');
sleep(1);
debug(Timer::read('test') . ' ms');

\Drupal::logger('modulename')->info('Hello World!');
\Drupal::logger('modulename')->error('It\'s error');

// MODULENAME.module
 
/**
 * Implements hook_page_attachments().
 */
function MODULENAME_page_attachments(array &$page) {
  $page['#attached']['library'][] = 'MODULENAME/libraryname';
}

/** @var \Drupal\Core\Session\AccountProxyInterface $current_user */
$current_user = \Drupal::currentUser();

$current_user_uid = \Drupal::currentUser()->id();
/** @var \Drupal\user\Entity\User $current_user */
$current_user = \Drupal\user\Entity\User::load($current_user_uid);

if (\Drupal::currentUser()->isAnonymous()) {
  ...
}

if (\Drupal::currentUser()->hasPermission('administer site configuration')) {
  ...
}

if (in_array('administrator', \Drupal::currentUser()->getRoles())) {
  // Current user has role "administrator"
}
if (array_intersect(['administrator', 'editor'], \Drupal::currentUser()->getRoles())) {
  // Current user has role "administrator" or "editor"
}

// $_GET
$nid = \Drupal::request()->query->get('nid');
$all_get_params = \Drupal::request()->query->all();
 
// $_POST
$nid = \Drupal::request()->request->get('nid');
$all_post_params = \Drupal::request()->request->all();
 
// $_COOKIE
$nid = \Drupal::request()->cookies->get('nid');
$all_cookie_params = \Drupal::request()->cookies->all();

my-library:
  js:
    my-scripts.js: {}
  dependencies:
    - core/jquery.cookie   # <------

// Установить куку
$.cookie('cookie_name', 'cookie_value', {path: drupalSettings.path.baseUrl});
 
// Прочитать куку
var cookieValue = $.cookie('cookie_name');
 
// Удалить куку
$.removeCookie('cookie_name', {path: drupalSettings.path.baseUrl});

// Сохранить объект
var exampleObject = {
  foo: 'bar'
};
$.cookie('cookie_name', JSON.stringify(exampleObject), {path: drupalSettings.path.baseUrl});
 
// Прочитать объект
var exampleObject = JSON.parse($.cookie('cookie_name'));

$string = \Drupal\Component\Utility\Html::escape('<b>Hello</b>'); // Переменная будет содержать "&lt;b&gt;Hello&lt;/b&gt;"

$string = new \Drupal\Component\Render\FormattableMarkup('My name is: @name', [
  '@name' => $name,
]);

$string = new \Drupal\Component\Render\FormattableMarkup('My name is: @name', [
  '@name' => \Drupal\Core\Render\Markup::create('<b>Dries</b>'),
]);

$string = \Drupal::translation()->formatPlural(123, '@count day', '@count days');

$truncated_text = \Drupal\Component\Utility\Unicode::truncate($text, 128);

use Drupal\Component\Serialization\Json;
$string = Json::encode($array);
$array = Json::decode($string);

$default_language = \Drupal::languageManager()->getDefaultLanguage();
$default_langcode = $default_language->getId();

$current_language = \Drupal::languageManager()->getCurrentLanguage();
$current_langcode = $current_language->getId();

/** @var \Drupal\Core\Datetime\DateFormatterInterface $date_formatter */
$date_formatter = \Drupal::service('date.formatter');
$formatted_date = $date_formatter->format(1558730206, 'short');

$ vendor/bin/drush config-import --partial --source=modules/modulename/config/install

\Drupal::service('plugin.manager.mail')->mail(
  'modulename',
  'example_mail_key',
  'to@gmail.com',
  'en',
  ['myvar' => 123]
);

function MODULENAME_mail($key, &$message, $params) {
  if ($key == 'example_mail_key') {
    $message['subject'] = 'Example email subject';
    $message['body'][] = 'Example email body. myvar = ' . $params['myvar'];
  }
}

\Drupal::service('plugin.manager.mail')->mail('system', 'example_mail_key', 'example@gmail.com', 'en', [
  'context' => [
    'subject' => 'Subject',
    'message' => \Drupal\Core\Render\Markup::create('Message'),
  ],
]);

$ip = \Drupal::request()->getClientIp();

$current_timestamp = \Drupal::time()->getCurrentTime();

$transliterated_string = \Drupal::transliteration()->transliterate('Привет Мир', 'ru');
// --> Privet Mir

// src/Controller/ExampleController.php
 
class ExampleController extends ControllerBase {
 
  public function export() {
    $response = new Response();
    $response->headers->set('Content-Type', 'text/csv; charset=utf-8');
    $response->headers->set('Content-Disposition', 'attachment; filename="example.txt"');
    $response->setContent('Hello World!');
 
    return $response;
  }
 
}

// 404
throw new NotFoundHttpException();
// 403
throw new AccessDeniedHttpException();

// modulename.tokens.inc
 
/**
 * Implements hook_token_info().
 */
function MODULENAME_token_info() {
  $token_info['tokens']['node']['example-token'] = [
    'name' => 'Example node token',
  ];
 
  return $token_info;
}
 
/**
 * Implements hook_tokens().
 */
function MODULENAME_tokens($type, $tokens, array $data, array $options, BubbleableMetadata $bubbleable_metadata) {
  $replacements = [];
 
  if ($type == 'node' && !empty($data['node'])) {
    $node = $data['node']; /** @var NodeInterface $node */
 
    foreach ($tokens as $name => $original) {
      if ($name == 'example-token') {
        $replacements[$original] = 'It\'s example token for node ' . $node->id();
      }
    }
  }
 
  return $replacements;
}

$string = \Drupal::token()->replace('Example string with [node:title] token', [
  'node' => Node::load(123),
]);

class ExampleController extends ControllerBase {
 
  public function exampleAction() {
    $meta_description = [
      '#tag' => 'meta',
      '#attributes' => [
        'name' => 'description',
        'content' => ['#plain_text' => 'Random text'],
      ],
    ];
 
    return [
      '#attached' => [
        'html_head' => [
          [$meta_description, 'description']
        ],
      ],
      ...
    ];
  }
 
}

administer modulename:
  title: 'Administer Modulename'

$data = ['foo' => 'bar'];
\Drupal::moduleHandler()->alter('my_data', $data);

function MODULENAME_my_data_alter(&$data) {
  $data['foo'] = 'baz';
}

$formatted_text = check_markup('Hello world', 'full_html');

$comment_count = (int)$entity->get('field_comment')->comment_count;

/**
 * Implements hook_query_TAG_alter(): comment_filter.
 */
function hook_query_comment_filter_alter(QueryAlterableInterface $query) {
  if ($query instanceof PagerSelectExtender) {
    $order_by = &$query->getOrderBy();
    unset($order_by['c.cid']);
    $query->orderBy('c.created', 'DESC');
  }
}

function _get_comment_page($entity_id, $comment_cid, $per_page) {
  $comment_index = \Drupal::database()
    ->select('comment_field_data')
    ->condition('entity_id', $entity_id)
    ->condition('status', 1)
    ->condition('cid', $comment_cid, '>=')
    ->countQuery()
    ->execute()
    ->fetchField();
 
  return ceil($comment_index / $per_page) - 1;
}

/**
 * Implements hook_views_pre_view().
 */
function MODULENAME_views_pre_view(ViewExecutable $view, $display_id, array &$args) {
  if ($view->id() == 'my_view_name') {
    if (\Drupal::currentUser()->hasPermission('administer comments')) {
      $view->removeHandler($view->current_display, 'filter', 'status');
    }
  }
}

/**
 * Implements hook_views_pre_view().
 */
function MODULENAME_views_pre_view(ViewExecutable $view, $display_id, array &$args) {
  if ($view->id() == 'my_view_name') {
    $view->setItemsPerPage(10);
  }
}

// src/EventSubscriber/ModulenameEventSubscriber.php
 
class ModulenameEventSubscriber implements EventSubscriberInterface {
 
  /**
   * {@inheritdoc}
   */
  public static function getSubscribedEvents() {
    $events['example_event_name'][] = ['onExampleEventName', 0];
    return $events;
  }
 
  /**
   * Event callback.
   */
  public function onExampleEventName(Event $event) {
    ...
  }
 
}

# mosulename.services.yml

services:
  modulename.event_subscriber:
    class: Drupal\modulename\EventSubscriber\ModulenameEventSubscriber
    tags:
      - { name: event_subscriber }

vendor/bin/drush eval "print_r(gd_info())"

// modulename.install
 
/**
 * Implements hook_install().
 */
function modulename_install() {
  module_set_weight('modulename', 123);
}

// modulename.install
 
/**
 * Set module weight.
 */
function modulename_update_8001() {
  module_set_weight('modulename', 123);
}

// С помощью статического метода load()
$node = \Drupal\node\Entity\Node::load(123);
$term = \Drupal\taxonomy\Entity\Term::load(234);
 
// С помощью сервиса entity_type.manager
$node = \Drupal::entityTypeManager()->getStorage('node')->load(123);
$term = \Drupal::entityTypeManager()->getStorage('taxonomy_term')->load(234);

$category_field = \Drupal::service('entity_field.manager')->getFieldDefinitions('node', 'page')['field_category'];
$category_field_storage = $field_definition->getFieldStorageDefinition();

if (!$entity->get('field_example')->isEmpty()) {
  // field_example not empty
}

$label_key = $entity->getEntityType()->getKey('label');

if ($entity->hasField('field_example')) {
  ...
}

$entity_type = 'node';
$entity_bundle = 'page';
$field_name = 'field_example';
 
$field_storage = FieldStorageConfig::loadByName($entity_type, $field_name);
if ($field_storage && in_array($entity_bundle, $field_storage->getBundles())) {
  ...
}

// Если есть доступ к объекту сущности
$field_example_label = $entity->get('field_example')->getFieldDefinition()->getLabel();
// Иначе
$field_example_label = \Drupal::service('entity_field.manager')->getFieldDefinitions('node', 'page')['field_example']->getLabel();

$date_start = $node->field_daterange->start_date;
$date_end = $node->field_daterange->end_date;
$days_between_dates = $date_end->diff($date_start)->format('%a');

if ($node->get('title')->getFieldDefinition() instanceof BaseFieldDefinition) {
  // Поле title является базовым
}
if ($node->get('field_example')->getFieldDefinition() instanceof FieldConfigInterface) {
  // Поле field_example является настраиваемым
}

$field_example_items = $entity->get('field_example');
$allowed_values = options_allowed_values($field_example_items->getFieldDefinition()->getFieldStorageDefinition(), $entity);
$value_label = $allowed_values[$field_example_items->value];

// Способ 1
$node_type = $node->get('type')->entity;
 
// Способ 2
$node_type = NodeType::load($node->bundle());

$file = \Drupal\file\Entity\File::load(123); /** @var \Drupal\file\FileInterface $file */
$file_relative_url = $file->createFileUrl(); // /sites/default/files/example.jpg
$file_absolute_url = $file->createFileUrl(FALSE); // http://example.com/sites/default/files/example.jpg
$file_uri = $file->getFileUri(); // public://example.jpg

$file = $entity->get('field_example_file')->entity; /** @var \Drupal\file\FileInterface $file */
$file_url = $file->createFileUrl(); // /sites/default/files/example.jpg
$file_uri = $file->getFileUri(); // public://example.jpg

$file_uri = 'public://example.jpg';
if ($files = \Drupal::entityTypeManager()->getStorage('file')->loadByProperties(['uri' => $file_uri])) {
  $file = current($files); /** @var FileInterface $file */
}

$uri = 'public://example.jpg';
$file = \Drupal\file\Entity\File::create([
  'uri' => $uri,
  'filename' => basename($uri),
]);
$file->save();

$file_id = 123;
$entity->get('field_file')->appendItem(['target_id' => $file_id]);

$file = \Drupal\file\Entity\File::load(123);
$entity->get('field_file')->appendItem($file);

$file = system_retrieve_file('http://example.com/image.jpg', 'public://image.jpg', TRUE);

$node = \Drupal\node\Entity\Node::load(123);
$node->delete();

vendor/bin/drush entity-delete node 123

$entity_storage = \Drupal::entityTypeManager()->getStorage('node');
$entities = $entity_storage->loadMultiple([1, 2, 3]);
$entity_storage->delete($entities);

vendor/bin/drush entity-delete node 1,2,3

$entity_storage = \Drupal::entityTypeManager()->getStorage('node');
$entities = $entity_storage->loadByProperties(['type' => 'article']);
$entity_storage->delete($entities);

vendor/bin/drush entity-delete node --bundle=article

/** @var TermStorageInterface $term_storage */
$term_storage = \Drupal::entityTypeManager()->getStorage('taxonomy_term');
$terms = $term_storage->loadByProperties(['vid' => 'category']);
foreach ($terms as $term) {
  $term->save();
}

/** @var EntityFieldManagerInterface $entity_field_manger */
$entity_field_manger = \Drupal::service('entity_field.manager');
$entity_reference_fields = $entity_field_manger->getFieldMapByFieldType('entity_reference');

/** @var EntityFieldManager $entity_field_manager */
$entity_field_manager = \Drupal::service('entity_field.manager');
$article_fields = $entity_field_manager->getFieldDefinitions('node', 'article');

$path = \Drupal::service('path.alias_manager')->getPathByAlias('/example-url-alias');
if (preg_match('/node\/(\d+)/', $path, $matches)) {
  $node = \Drupal\node\Entity\Node::load($matches[1]);
}

/**
 * Implements hook_entity_update().
 */
function hook_entity_update(EntityInterface $entity) {
  $field_example_items = $entity->get('field_example');
  $original_field_example_items = $entity->original->get('field_example');
  if ($field_example_items ->hasAffectingChanges($original_field_example_items, $field_example_items->getLangcode())) {
    // field_example changed
  }
}

/** @var TermStorageInterface $term_storage */
$term_storage = \Drupal::entityTypeManager()->getStorage('taxonomy_term');
 
// Способ 1 - по id термина. Получает только непосредственных детей термина 123.
// Результат не отсортирован.
$children_terms = $term_storage->loadChildren(123, 'category'); /** @var TermInterface[] $children_terms */
 
// Способ 2 - по объекту термина. Получает только непосредственных детей термина $term.
// Результат не отсортирован.
$children_terms = $term_storage->getChildren($term); /** @var TermInterface[] $children_terms */
 
// Способ 3 - по id термина. Получает всех детей термина 123 независимо от вложенности.
// Переданный термин в массив не добавляется.
// Результат отсортирован по весу термина.
$children_terms = $term_storage->loadTree('category', 123, NULL, TRUE); /** @var TermInterface[] $children_terms */

/** @var TermStorageInterface $term_storage */
$term_storage = \Drupal::entityTypeManager()->getStorage('taxonomy_term');
 
// Получает всех родителей независимо от глубины. В массиве так же возвращается и исходный термин.
$parents = $term_storage->loadAllParents(123); /** @var TermInterface[] $parents */
 
// Получает непосредственных родителей термина 123. В большинстве случаев это будет массив из одного элемента.
$parents = $term_storage->loadParents(123); /** @var TermInterface[] $parents */
 
// Непосредственные родители так же доступны через поле термина "parent"
$parents_items = $term->get('parent'); /** @var EntityReferenceFieldItemListInterface $parents_items */

/**
 * Implements hook_theme().
 */
function MODULENAME_theme() {
  return [
    'node' => [
      'render element' => 'elements',
    ],
  ];
}

{{ content }}

// THEMENAME.theme
 
/**
 * Preprocess function for html.html.twig.
 */
function THEMENAME_preprocess_html(&$vars) {
  $vars['#attached']['drupalSettings']['path']['currentThemePath'] = $vars['directory'];
}

# THEMENAME.libraries.yml
 
my-library-name:
  js: ...
  dependencies:
    - core/drupalSettings

$current_theme = \Drupal::service('theme.manager')->getActiveTheme(); /** @var ActiveTheme $current_theme */
// Машинное имя темы
$current_theme_machine_name = $current_theme->getName();
// Информация из файла themename.info.yml
$current_theme_info = $current_theme->getExtension()->info;

$default_theme_name = \Drupal::config('system.theme')->get('default');

libraries:
  - themename/libraryname

my-library:
  js:
    js/my-library.js: {}
  header: true # <--

$node = \Drupal\node\Entity\Node::load(123);
 
// Render-array поля, прошедшего через field.html.twig
$field_example_build = $node->get('field_example')->view('full');
// Render-array первого значения поля, прошедшего через форматтер
$field_example_build = $node->get('field_example')[0]->view('full');

$node = \Drupal\node\Entity\Node::load(123);
$node_view_builder = \Drupal::entityTypeManager()->getViewBuilder('node');
$node_build = $node_view_builder->view($node, 'teaser');

/**
 * Implements hook_theme().
 */
function MODULENAME_theme() {
  return [
    'my_template' => [
      'variables' => [
        'my_variable' => NULL,
      ],
    ],
  ];
}

<div class="my-template">{{ my_variable }}</div>

$variables['my_html_var'] = \Drupal\Core\Render\Markup::create('<b>Hello</b> <i>World</i>');

/**
 * Implements hook_theme().
 */
function themename_theme() {
  return [
    'example_form' => [
      'render element' => 'form',
    ],
  ];
}

<form{{ attributes }}>
  <header>
    {{ form.element1 }}
    {{ form.element2 }}
  </header>
  {{ form.without('element1', 'element2') }}
</form>

$render_array = [
  '#theme' => 'status_messages',
  '#message_list' => [
    'warning' => ['Warning!'],
  ],
];
$output = render($render_array);

\Drupal::service('cache_tags.invalidator')->invalidateTags(['node:123']);

$build = [
  '#theme' => 'table',
  '#header' => ['ID', 'Title', 'Date'],
  '#rows' => [
    [1, 'Title 1', '01.01.2019'],
    [2, 'Title 2', '02.01.2019'],
    [3, 'Title 3', '03.01.2019'],
  ],
  '#empty' => 'Empty...',
];

/**
 * Implements hook_entity_extra_field_info().
 */
function MODULENAME_entity_extra_field_info() {
  $extra_fields['node']['article']['display']['author'] = [
    'label' => t('Author name'),
    'weight' => 0,
  ];
 
  return $extra_fields;
}
 
/**
 * Implements hook_ENTITY_TYPE_view(): node.
 */
function MODULENAME_node_view(array &$build, NodeInterface $node, EntityViewDisplayInterface $display, $view_mode) {
  if ($display->getComponent('author')) {
    $build['author'] = ['#markup' => $node->getOwner()->getDisplayName()];
  }
}

function THEMENAME_preprocess_menu(&$vars) {
  THEMENAME_preprocess_menu_items($vars['items']);
}
 
function THEMENAME_preprocess_menu_items(&$items) {
  foreach ($items as &$item) {
    $item['title'] = Markup::create($item['title']);
 
    if ($item['below']) {
      THEMENAME_preprocess_menu_items($item['below']);
    }
  }
}

function THEMENAME_preprocess_menu__main(&$vars) {
  $vars['attributes']['class'][] = 'dragscroll';
}

function THEMENAME_preprocess_block__main_menu(&$vars) {
  $vars['attributes']['class'][] = 'my-block-class';
  $vars['content_attributes']['class'][] = 'my-content-class';
}

$build = [
  '#theme' => 'item_list',
  '#items' => [
    1 => 'Item 1',
    2 => [
      'value' => ['#markup' => 'Item 2'],
      'below' => [
        '#theme' => 'item_list',
        '#items' => [
          1 => 'Item 2.1',
          2 => 'Item 2.2',
        ],
      ],
      '#wrapper_attributes' => [
        'class' => ['open'],
      ],
    ],
    3 => 'Item 3',
  ],
];

<ul>
  <li>Item 1</li>
  <li class="open">
    Item 2
    <ul>
      <li>Item 2.1</li>
      <li>Item 2.2</li>
    </ul>
  </li>
  <li>Item 3</li>
</ul>

$build = [
  '#theme' => 'item_list',
  '#items' => [
    0 => [
      'item' => ['#markup' => 'Item 1'],
      '#wrapper_attributes' => ['class' => ['item-1-class']],
    ],
    1 => [
      'item' => ['#markup' => 'Item 2'],
      '#wrapper_attributes' => ['class' => ['item-2-class']],
    ],
  ],
];

<ul>
  <li class="item-1-class">Item 1</li>
  <li class="item-2-class">Item 2</li>
</ul>

function THEMENAME_preprocess_views_view_field__content_recent__title(&$vars) {
  $vars['output'] = 'new field output';
}

/**
 * Preprocess function for views-view--example-view.html.twig.
 */
function THEMENAME_preprocess_views_view__example_view(&$vars) {
  $view = $vars['view']; /** @var ViewExecutable $view */
  $vars['attributes']['class'][] = 'views--count-' . count($view->result);
}

/**
 * Implements hook_comment_links_alter().
 */
function hook_comment_links_alter(array &$links, CommentInterface $entity, array &$context) {
  if (isset($links['comment']['#links']['comment-reply'])) {
    unset($links['comment']['#links']['comment-reply']);
  }
}

// src/ModulenameEventSubscriber.php
 
/**
 * Event Subscriber MyEventSubscriber.
 */
class ModulenameEventSubscriber implements EventSubscriberInterface {
 
  /**
   * {@inheritdoc}
   */
  public static function getSubscribedEvents() {
    $events[KernelEvents::VIEW][] = ['onKernelView', 10];
    return $events;
  }
 
  /**
   * KernelEvents::VIEW event callback.
   */
  public function onKernelView(GetResponseForControllerResultEvent $event) {
    if (\Drupal::routeMatch()->getRouteName() == 'comment.reply') {
      $result = $event->getControllerResult();
      $result['commented_entity']['#access'] = FALSE;
      $event->setControllerResult($result);
    }
  }
 
}

# modulename.services.yml
 
services:
  modulename.event_subscriber:
    class: Drupal\modulename\ModulenameEventSubscriber
    tags:
      - { name: event_subscriber }

@keyframes dialog-fade-in {
  from {
    opacity: 0;
  }
  to {
    opacity: 1;
  }
}
 
.ui-widget-overlay,
.ui-dialog {
  animation-duration: 0.3s;
  animation-name: dialog-fade-in;
}

{% if not node.field_example.isEmpty() %}
   field_example is not empty
{% endif %}

{% if content.field_example[0] %}
   field_example is not empty
{% endif %}

{% if node.field_example|length > 1 %}
   Field items count more 1
{% endif %}

{{ content.field_example }}

{{ content.field_example[0] }}

{{ content.field_example|children }}

{{ node.field_example.value }}
 
{# Или так, если в значении поля есть html код (небезопасно!) #}
{{ node.field_example.value|raw }}

{% if my_array is not empty %}
  ...
{% endif %}

{% if my_array|length > 0 %}
  ...
{% endif %}

{% if (example_array.foo is defined) %}
  {{ example_array.foo }}
{% endif %}
 
{% if (example_array.foo is not defined) %}
  Empty message...
{% endif %}

{% for key, element in elements if key|first != '#' %}
  {{ element }}
{% endfor %}

{% for element in elements|children %}
  {{ element }}
{% endfor %}

{{ element['#object'].title.value }}

{{ file_url(node.field_image.entity.uri.value) }}

{{ node.created.value|format_date('custom', 'd.m.Y') }}

{{ path('entity.node.canonical', {node: 123}) }}

{{ 'Home'|t }}
{{ 'Order'|t({}, {'context': 'Commerce'}) }}

{% trans %}
  {{ count }} review
{% plural count %}
  {{ count }} reviews
{% endtrans %}

{% if logged_in %}
  Current user is authenticated
{% else %}
  Current user is anonymouse
{% endif %}

// MODULENAME.module
 
use Drupal\Core\Form\FormStateInterface;
 
/**
 * Implements hook_form_FORM_ID_alter(): user_register_form.
 */
function MODULENAME_form_user_register_form_alter(&$form, FormStateInterface $form_state) {
  $form['terms_of_use'] = [
    '#type' => 'checkbox',
    '#title' => t('I agree with terms and conditions.'),
    '#required' => TRUE,
  ];
}

/**
 * Implements hook_form_FORM_ID_alter(): views_exposed_form.
 */
function MODULENAME_form_views_exposed_form_alter(&$form, FormStateInterface $form_state) {
  $view = $form_state->get('view'); /** @var ViewExecutable $view */
  if ($view->id() == 'example_views' && $view->current_display == 'example_display') {
    ...
  }
}

namespace Drupal\modulename\Form;
 
use Drupal\Core\Form\FormBase;
use Drupal\Core\Form\FormStateInterface;
 
class ExampleForm extends FormBase {
 
  public function getFormId() {
    return 'example_form';
  }
 
  public function buildForm(array $form, FormStateInterface $form_state) {
    $form['example_text'] = [
      '#type' => 'textfield',
      '#title' => $this->t('Text'),
    ];
    $form['submit'] = [
      '#type' => 'submit',
      '#value' => $this->t('Submit'),
    ];
    return $form;
  }
 
  public function submitForm(array &$form, FormStateInterface $form_state) {
    $text = $form_state->getValue('example_text');
  }
 
}

$ vendor/bin/drush generate form-simple

public function buildForm(array $form, FormStateInterface $form_state) {
  ...
  $form['#method'] = 'get';
  $form['#action'] = \Drupal::urlGenerator()->generateFromRoute('example.route');
  ...
}

public function buildForm(array $form, FormStateInterface $form_state) {
  ...
  $form['#cache']['max-age'] = 0;
  ...
}

public function buildForm(array $form, FormStateInterface $form_state) {
  ...
  $form['#pre_render'][] = [$this, 'preRender'];
 
  return $form;
}
 
public function preRender($form) {
  unset($form['form_id']);
  unset($form['form_build_id']);
  unset($form['form_token']);
  unset($form['submit']['#name']);
 
  return $form;
}

public function buildForm(array $form, FormStateInterface $form_state) {
  ...
  $form['#token'] = FALSE;
 
  return $form;
}

modulename.example_form:
  path: '/example/form'
  defaults:
    _form: 'Drupal\MODULENAME\Form\ExampleForm'
    _title: 'Example form'
  requirements:
    _permission: 'access content'

modulename.example_form:
  path: '/node/{node}/example-form'
  defaults:
    _form: 'Drupal\modulename\Form\ExampleForm'
    _title: 'Example form'
  requirements:
    _permission: 'access content'

class ExampleForm extends FormBase {
  ...
  public function buildForm(array $form, FormStateInterface $form_state, NodeInterface $node = NULL) {
    ...
  }
}

/**
 * @Block(
 *   id = "my_block_with_form",
 *   admin_label = @Translation("My block with form"),
 *   category = @Translation("Forms")
 * )
 */
class MyBlockWithForm extends BlockBase {
  public function build() {
    return [
      'form' => \Drupal::formBuilder()->getForm('Drupal\modulename\Form\ExampleForm')
    ];
  }
}

vendor/bin/drush generate form-config

foreach (\Drupal\Core\Render\Element::children($form) as $key) {
  debug($form[$key]);
}

class ExampleForm extends FormBase {
 
  public function buildForm(array $form, FormStateInterface $form_state, NodeInterface $node = NULL) {
    ...
  }
 
  public function submitForm(array &$form, FormStateInterface $form_state) {
    /** @var NodeInterface $node */
    $node = $form_state->getBuildInfo()['args'][0];
  }
 
}

public function buildForm(array $form, FormStateInterface $form_state) {
  $form['my_element'] = [
    '#type' => 'number',
    '#default_value' => 1,
  ];
 
  $my_element_current_value = $form_state->getValue('my_element', $form['my_element']['#default_value']);
}

public function submitForm(array &$form, FormStateInterface $form_state) {
  ...
  $form_state->set('example_data', 123);
}

$data = $form_state->get('example_data');

$form['example_select'] = [
  '#type' => 'select',
  '#options' => [
    1 => 'Show',
    2 => 'Hide',
  ],
];
 
$form['dependent_select'] = [
  '#type' => 'select',
  '#options' => [...],
  '#states' => [
    'visible' => [
      ':input[name="example_select"]' => ['value' => 1],
    ],
  ],
];

$form['second_element'] = [
  ...
  '#states' => [
    'invisible' => [
      ':input[name="first_element"]' => [
        ['value' => 'xxx'],
      ],
    ],
  ],
];

$form['#attributes']['novalidate'] = 'novalidate';

class ExampleForm extends FormBase {
 
  /**
   * {@inheritDoc}
   */
  public function buildForm(array $form, FormStateInterface $form_state) {
    ...
 
    $form['submit'] = [
      '#type' => 'submit',
      '#value' => $this->t('Submit'),
      '#ajax' => [
        'callback' => '::ajaxSubmit',
      ],
    ];
 
    $form['#attached']['library'][] = 'core/drupal.dialog.ajax';
 
    return $form;
  }
 
  /**
   * Ajax submit callback.
   */
  public function ajaxSubmit(array $form, FormStateInterface $form_state) {
    $response = new AjaxResponse();
 
    if ($form_state->hasAnyErrors()) {
      $response->addCommand(new OpenModalDialogCommand($this->t('Error'), ['#type' => 'status_messages']));
    }
    else {
      ...
    }
 
    return $response;
  }
 
}

$response->addCommand(new InvokeCommand('.my-element', 'addClass', ['my-new-class']));
$response->addCommand(new InvokeCommand('.my-element', 'removeClass', ['my-old-class']));

$response->addCommand(new InvokeCommand('.my-element', 'trigger', ['click']));

public function validateForm(array &$form, FormStateInterface $form_state) {
  if (!\Drupal::flood()->isAllowed('example_form', 1)) {
    $form_state->setErrorByName('', $this->t('You cannot send more.'));
  }
}
 
public function submitForm(array &$form, FormStateInterface $form_state) {
  ...
  \Drupal::flood()->register('example_form');
}

public function buildForm(array $form, FormStateInterface $form_state) {
  $form['foo'] = [
    '#type' => 'textfield',
  ];
  $form['bar'] = [
    '#tree' => TRUE,
  ];
  $form['bar']['baz'] = [
    '#type' => 'textfield',
  ];
}
 
public function submitForm(array &$form, FormStateInterface $form_state) {
  $foo_value = $form_state->getValue('foo');
  $baz_value = $form_state->getValue(['bar', 'baz']);
}

$form['table'] = [
  '#type' => 'table',
  '#header' => ['Key', 'Value'],
];
 
foreach ([1, 2, 3] as $key) {
  $form['table'][$key]['key'] = [
    '#markup' => 'Key #' . $key,
  ];
 
  $form['table'][$key]['value'] = [
    '#type' => 'textfield',
    '#title' => 'Value #' . $key,
  ];
}

class ExampleForm extends FormBase {
 
  /**
   * {@inheritDoc}
   */
  public function buildForm(array $form, FormStateInterface $form_state) {
    $rows = [
      1 => ['nid' => 1, 'title' => 'First node'],
      2 => ['nid' => 2, 'title' => 'Second node'],
      3 => ['nid' => 3, 'title' => 'Third node'],
    ];
 
    $form['nodes'] = [
      '#type' => 'tableselect',
      '#header' => [
        'nid'   => 'Node ID',
        'title' => 'Node title',
      ],
      '#options' => $rows,
      '#empty' => 'Empty...',
    ];
 
    $form['delete'] = [
      '#type' => 'submit',
      '#value' => 'Delete selected',
    ];
 
    return $form;
  }
 
  /**
   * {@inheritDoc}
   */
  public function submitForm(array &$form, FormStateInterface $form_state) {
    foreach ($form_state->getValue('nodes') as $nid => $state) {
      if ($state) {
        Node::load($nid)->delete();
      }
    }
  }
 
}

$form['element'] = [
  '#type' => 'textfield',
  '#title' => 'Element',
  '#theme_wrappers' => [], // <--
];

public function buildForm(array $form, FormStateInterface $form_state) {
  $form['upload'] = [
    '#type' => 'file',
    '#title' => t('File'),
  ];
 
  ...
 
  return $form;
}
 
public function submitForm(array &$form, FormStateInterface $form_state) {
  $file_system = \Drupal::service('file_system'); /** @var FileSystemInterface $file_system */
  $all_files = \Drupal::request()->files->get('files', []); /** @var UploadedFile[] $all_files */
  if ($all_files['upload']) {
    $file_system->move($all_files['upload']->getRealPath(), 'public://file.' . $all_files['upload']->getExtension());
  }
}

$or_conditions = $query->orConditionGroup();
$or_conditions->condition('n.status', 0);
$or_conditions->condition('n.status', 1);
$query->condition($or_conditions);
$query->condition('n.type', 'page');
// Сгенерирует условие:
// WHERE (n.status = 0 OR n.status = 1) AND n.type = 'page'

$query->isNull('field_name');
$query->isNotNull('field_name');

$count = \Drupal::database()
  ->select('node')
  ->condition('type', 'page')
  ->countQuery() // <--
  ->execute()
  ->fetchField();

// Max
$query = \Drupal::database()->select('node', 'n');
$query->addExpression('MAX(n.nid)');
$max_nid = $query->execute()->fetchField();
 
// Min
$query = \Drupal::database()->select('node', 'n');
$query->addExpression('MIN(n.nid)');
$min_nid = $query->execute()->fetchField();

$subquery = \Drupal::database()
  ->select('taxonomy_index', 't')
  ->fields('t')
  ->where('t.nid = n.nid');
 
$query = \Drupal::database()
  ->select('node', 'n')
  ->fields('n')
  ->exists($subquery);

SELECT * FROM node n
WHERE EXISTS (
  SELECT * FROM taxonomy_index t
  WHERE t.nid = n.nid
)

$query = \Drupal::database()
  ->select('node', 'n')
  ->condition('n.title', '%' . \Drupal::database()->escapeLike('world') . '%', 'LIKE');

$nids = \Drupal::entityQuery('node');
  ->condition('type', 'article');
  ->condition('status', NodeInterface::PUBLISHED);
  ->condition('field_foo', 'bar')
  ->execute();

$nids = \Drupal::entityQuery('node');
  ->condition('type', 'article');
  ->condition('status', NodeInterface::PUBLISHED);
  ->condition('field_foo', 'bar')
  ->range(0, 1)
  ->execute();
if ($nids) {
  $node = Node::load(current($nids));
}

$node_query = \Drupal::entityQuery('node');
$node_query->condition($node_query->andConditionGroup()->condition('field_example', 'foo'));
$node_query->condition($node_query->andConditionGroup()->condition('field_example', 'bar'));
$nids = $node_query->execute();

// Условие "поле field_foo не должно иметь значений"
$entity_query->notExists('field_foo');
// Или
$entity_query->condition('field_bar', NULL, 'IS NULL');
 
// Обратное условие "поле field_bar должно иметь хотя бы одно значение"
$entity_query->exists('field_bar');
// Или
$entity_query->condition('field_bar', NULL, 'IS NOT NULL');

$node_query->notExists('field_example.1.value');

$news_count = \Drupal::entityQuery('node')
  ->condition('type', 'news')
  ->count()
  ->execute();

$node_query = \Drupal::entityQuery('node');
...
$node_query->addTag('debug');
$result = $node_query->execute();

$result = \Drupal::entityQuery('node')
  ->sort('nid', 'DESC')
  ->range(0, 1)
  ->execute();
$last_nid = $result ? current($result) : NULL;

modulename.settings:
  title: 'Modulename settings'
  description: 'Settings for modulename.'
  parent: system.admin_config_system
  route_name: modulename.settings

entity.node.my_tab:
  path: '/node/{node}/my-tab'
  defaults:
    _controller: '\Drupal\modulename\Controller\MyController::myAction'
    _title: 'My tab'
  requirements:
    _permission: 'access content'

entity.node.my_tab:
  route_name: entity.node.my_tab
  base_route: entity.node.canonical
  title: My tab
  weight: 2

// Системный адрес. Аналог current_path().
$current_system_path = \Drupal::service('path.current')->getPath();
 
// Синоним адреса. Аналог request_path().
$current_system_path = \Drupal::service('path.current')->getPath();
$current_path_alias = \Drupal::service('path.alias_manager')->getAliasByPath($current_system_path);
 
// Полный путь из строки браузера, с GET параметрами. Аналог request_uri().
$current_request_uri = \Drupal::request()->getRequestUri();

$base_path = base_path();

if (\Drupal::service('router.admin_context')->isAdminRoute()) {
  ...
}

if (\Drupal::service('path.matcher')->isFrontPage()) {
  ...
}

$current_route_name = \Drupal::routeMatch()->getRouteName();

if (\Drupal::routeMatch()->getRouteName() == 'entity.node.canonical') {
  ...
}

$nid = \Drupal::routeMatch()->getRawParameter('node'); // Integer
$node = \Drupal::routeMatch()->getParameter('node'); // Node object

modulename.example_route:
  title: 'Example'
  route_name: modulename.example_route
  menu_name: account
  options:
    attributes:
      class:
        - use-ajax

/**
 * Implements hook_menu_links_discovered_alter().
 */
function modulename_menu_links_discovered_alter(&$links) {
  $links['user.logout']['options']['attributes']['class'][] = 'use-ajax';
}

// Вернёт http://example.com/sites/default/files/example.jpg
$file_url = file_create_url('public://example.jpg');

$destination_array = \Drupal::destination()->getAsArray();
$url = \Drupal::urlGenerator()->generateFromRoute('example.route', [], ['query' => $destination_array]);

class ExampleController extends ControllerBase {
 
  public function exampleAction() {
    return $this->redirect('<front>');
  }
 
}

$path = \Drupal::service('path.alias_manager')->getPathByAlias('/example-url-alias');

$node_alias = $node->get('path')->alias; // "/example/node/path"

catalog/[term:parents:join-path]/[term:name]

$image_uri = 'public://image.jpg';
$image_style = ImageStyle::load('thumbnail'); /** @var ImageStyleInterface $image_style */
 
$absolute_url = $image_style->buildUrl($image_uri); // http://example.com/sites/default/files/styles/thumbnail/public/image.jpg?itok=BN-lOMvj
$relative_url = file_url_transform_relative($absolute_url); // /sites/default/files/styles/thumbnail/public/image.jpg?itok=BN-lOMvj