drupal-code-patterns

About the "Reference:" paths below

Some patterns point to the contrib Examples module for extended reference. These templates are SELF-SUFFICIENT — the references are optional extra reading. Before following one, check it exists:

ssh web test -d $DDEV_DOCROOT/modules/contrib/examples && echo "examples available" || echo "examples not installed — skip the references"

Service Class

<?php

declare(strict_types=1);

namespace Drupal\mymodule\Service;

use Drupal\Core\Entity\EntityTypeManagerInterface;
use Drupal\Core\Session\AccountProxyInterface;
use Psr\Log\LoggerInterface;

final class MyService {

  public function __construct(
    private readonly EntityTypeManagerInterface $entityTypeManager,
    private readonly AccountProxyInterface $currentUser,
    private readonly LoggerInterface $logger,
  ) {}

  public function process(string $input): array {
    if (empty($input)) {
      throw new \InvalidArgumentException('Input cannot be empty.');
    }
    $this->logger->info('Processing: @input', ['@input' => $input]);
    return ['result' => $input];
  }

}

Form (FormBase)

Reference: $DDEV_DOCROOT/modules/contrib/examples/modules/form_api_example

<?php

declare(strict_types=1);

namespace Drupal\mymodule\Form;

use Drupal\Core\Form\FormBase;
use Drupal\Core\Form\FormStateInterface;
use Drupal\mymodule\Service\MyService;
use Symfony\Component\DependencyInjection\ContainerInterface;

final class MyForm extends FormBase {

  public function __construct(
    private readonly MyService $myService,
  ) {}

  public static function create(ContainerInterface $container): self {
    return new self($container->get('mymodule.my_service'));
  }

  public function getFormId(): string {
    return 'mymodule_my_form';
  }

  public function buildForm(array $form, FormStateInterface $form_state): array {
    $form['name'] = [
      '#type' => 'textfield',
      '#title' => $this->t('Name'),
      '#required' => TRUE,
      '#maxlength' => 255,
    ];
    $form['actions'] = [
      '#type' => 'actions',
      'submit' => ['#type' => 'submit', '#value' => $this->t('Submit')],
    ];
    return $form;
  }

  public function validateForm(array &$form, FormStateInterface $form_state): void {
    if (strlen($form_state->getValue('name')) < 3) {
      $form_state->setErrorByName('name', $this->t('Name must be at least 3 characters.'));
    }
  }

  public function submitForm(array &$form, FormStateInterface $form_state): void {
    $this->myService->process($form_state->getValue('name'));
    $this->messenger()->addStatus($this->t('Form submitted successfully.'));
  }

}