FormBase.php

<?php

/**
 * @file
 * Contains \Drupal\Core\Form\FormBase.
 */

namespace Drupal\Core\Form;

use Drupal\Core\Config\ConfigFactoryInterface;
use Drupal\Core\DependencyInjection\ContainerInjectionInterface;
use Drupal\Core\DependencyInjection\DependencySerializationTrait;
use Drupal\Core\Routing\LinkGeneratorTrait;
use Drupal\Core\Routing\UrlGeneratorTrait;
use Drupal\Core\StringTranslation\StringTranslationTrait;
use Symfony\Component\DependencyInjection\ContainerInterface;
use Symfony\Component\HttpFoundation\RequestStack;

/**
 * Provides a base class for forms.
 */
abstract class FormBase implements FormInterface, ContainerInjectionInterface {
  use StringTranslationTrait;
  use DependencySerializationTrait;
  use LinkGeneratorTrait;
  use UrlGeneratorTrait;

  /**
   * The request stack.
   *
   * @var \Symfony\Component\HttpFoundation\RequestStack
   */
  protected $requestStack;

  /**
   * The config factory.
   *
   * Subclasses should use the self::config() method, which may be overridden to
   * address specific needs when loading config, rather than this property
   * directly. See \Drupal\Core\Form\ConfigFormBase::config() for an example of
   * this.
   *
   * @var \Drupal\Core\Config\ConfigFactoryInterface
   */
  protected $configFactory;

  /**
   * The form error handler.
   *
   * @var \Drupal\Core\Form\FormErrorInterface
   */
  protected $errorHandler;

  /**
   * {@inheritdoc}
   */
  public static function create(ContainerInterface $container) {
    return new static();
  }

  /**
   * {@inheritdoc}
   */
  public function validateForm(array &$form, array &$form_state) {
    // Validation is optional.
  }

  /**
   * Retrieves a configuration object.
   *
   * This is the main entry point to the configuration API. Calling
   * @code $this->config('book.admin') @endcode will return a configuration
   * object in which the book module can store its administrative settings.
   *
   * @param string $name
   *   The name of the configuration object to retrieve. The name corresponds to
   *   a configuration file. For @code \Drupal::config('book.admin') @endcode,
   *   the config object returned will contain the contents of book.admin
   *   configuration file.
   *
   * @return \Drupal\Core\Config\Config
   *   A configuration object.
   */
  protected function config($name) {
    return $this->configFactory()->get($name);
  }

  /**
   * Gets the config factory for this form.
   *
   * When accessing configuration values, use $this->config(). Only use this
   * when the config factory needs to be manipulated directly.
   *
   * @return \Drupal\Core\Config\ConfigFactoryInterface
   */
  protected function configFactory() {
    if (!$this->configFactory) {
      $this->configFactory = $this->container()->get('config.factory');
    }
    return $this->configFactory;
  }

  /**
   * Sets the config factory for this form.
   *
   * @param \Drupal\Core\Config\ConfigFactoryInterface $config_factory
   *   The config factory.
   *
   * @return $this
   */
  public function setConfigFactory(ConfigFactoryInterface $config_factory) {
    $this->configFactory = $config_factory;
    return $this;
  }

  /**
   * Resets the configuration factory.
   */
  public function resetConfigFactory() {
    $this->configFactory = NULL;
  }

  /**
   * Gets the request object.
   *
   * @return \Symfony\Component\HttpFoundation\Request $request
   *   The request object.
   */
  protected function getRequest() {
    if (!$this->requestStack) {
      $this->requestStack = \Drupal::service('request_stack');
    }
    return $this->requestStack->getCurrentRequest();
  }

  /**
   * Sets the request stack object to use.
   *
   * @param \Symfony\Component\HttpFoundation\RequestStack $request_stack
   *   The request stack object.
   *
   * @return $this
   */
  public function setRequestStack(RequestStack $request_stack) {
    $this->requestStack = $request_stack;
    return $this;
  }

  /**
   * Gets the current user.
   *
   * @return \Drupal\Core\Session\AccountInterface
   *   The current user.
   */
  protected function currentUser() {
    return \Drupal::currentUser();
  }

  /**
   * Returns the service container.
   *
   * This method is marked private to prevent sub-classes from retrieving
   * services from the container through it. Instead,
   * \Drupal\Core\DependencyInjection\ContainerInjectionInterface should be used
   * for injecting services.
   *
   * @return \Symfony\Component\DependencyInjection\ContainerInterface $container
   *   The service container.
   */
  private function container() {
    return \Drupal::getContainer();
  }

  /**
   * Returns the form error handler.
   *
   * @return \Drupal\Core\Form\FormErrorInterface
   *   The form error handler.
   */
  protected function errorHandler() {
    if (!$this->errorHandler) {
      $this->errorHandler = \Drupal::service('form_builder');
    }
    return $this->errorHandler;
  }

  /**
   * Files an error against a form element.
   *
   * @param string $name
   *   The name of the form element.
   * @param array $form_state
   *   An associative array containing the current state of the form.
   * @param string $message
   *   (optional) The error message to present to the user.
   *
   * @see \Drupal\Core\Form\FormErrorInterface::setErrorByName()
   *
   * @return $this
   */
  protected function setFormError($name, array &$form_state, $message = '') {
    $this->errorHandler()->setErrorByName($name, $form_state, $message);
    return $this;
  }

}