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class SessionExampleForm in Examples for Developers 8

Same name and namespace in other branches
  1. 3.x modules/session_example/src/Form/SessionExampleForm.php \Drupal\session_example\Form\SessionExampleForm

Form to allow the user to store information in their session.

In this object we'll inject the session service. In the submission form we got the session from a Request object supplied by the routing system. Either of these work, because they're the same object. But we use injection here because the buildForm() method does not have an easy way to derive the Request object or the session.

Hierarchy

Expanded class hierarchy of SessionExampleForm

Related topics

Example: Session
Demonstrating how to manipulate sessions in Drupal 8.
1 string reference to 'SessionExampleForm'
session_example.routing.yml in session_example/session_example.routing.yml
session_example/session_example.routing.yml

File

session_example/src/Form/SessionExampleForm.php, line 23

Namespace

Drupal\session_example\Form
View source 
class SessionExampleForm extends FormBase {

  /**
   * The session object.
   *
   * We will use this to store information that the user submits, so that it
   * persists across requests.
   *
   * @var \Symfony\Component\HttpFoundation\Session\SessionInterface
   */
  protected $session;

  /**
   * The cache tag invalidator service.
   *
   * @var \Drupal\Core\Cache\CacheTagsInvalidatorInterface
   */
  protected $cacheTagInvalidator;

  /**
   * Constructs a new SessionExampleForm object.
   *
   * @param \Symfony\Component\HttpFoundation\Session\SessionInterface $session
   *   The session object.
   * @param \Drupal\Core\Cache\CacheTagsInvalidatorInterface $invalidator
   *   The cache tag invalidator service.
   */
  public function __construct(SessionInterface $session, CacheTagsInvalidatorInterface $invalidator) {
    $this->session = $session;
    $this->cacheTagInvalidator = $invalidator;
  }

  /**
   * {@inheritdoc}
   */
  public static function create(ContainerInterface $container) {
    return new static($container
      ->get('session'), $container
      ->get('cache_tags.invalidator'));
  }

  /**
   * {@inheritdoc}
   */
  public function getFormId() {
    return 'session_example_form';
  }

  /**
   * {@inheritdoc}
   */
  public function buildForm(array $form, FormStateInterface $form_state) {
    $form['description'] = [
      '#type' => 'item',
      '#title' => $this
        ->t('Session Data Form'),
      '#markup' => $this
        ->t('In this example form, data that you enter into the form will be saved into your session data, which persists until you log out of Drupal.'),
    ];
    $form['name'] = [
      '#type' => 'textfield',
      '#title' => $this
        ->t('Name'),
      '#placeholder' => $this
        ->t('Your name.'),
      '#default_value' => $this->session
        ->get('session_example.name', ''),
    ];
    $form['email'] = [
      '#type' => 'textfield',
      '#title' => $this
        ->t('Email'),
      '#placeholder' => $this
        ->t('Your email address.'),
      '#default_value' => $this->session
        ->get('session_example.email', ''),
    ];
    $form['quest'] = [
      '#type' => 'textfield',
      '#title' => $this
        ->t('Quest'),
      '#placeholder' => $this
        ->t('What is your quest?'),
      '#default_value' => $this->session
        ->get('session_example.quest', ''),
    ];
    $form['color'] = [
      '#type' => 'select',
      '#title' => $this
        ->t('Favorite Color'),
      '#options' => [
        '' => $this
          ->t('--'),
        'red' => $this
          ->t('Red'),
        'blue' => $this
          ->t('Blue'),
        'yellow' => $this
          ->t('Yellow'),
        'argggh' => $this
          ->t('Argggghhh!!'),
      ],
      '#default_value' => $this->session
        ->get('session_example.color', ''),
      '#description' => $this
        ->t('What is your favorite color?'),
    ];
    $form['save'] = [
      '#type' => 'submit',
      '#value' => $this
        ->t('Save'),
    ];
    $form['reset'] = [
      '#type' => 'submit',
      '#value' => $this
        ->t('Clear Session'),
      '#submit' => [
        '::submitClearSession',
      ],
    ];
    return $form;
  }

  /**
   * Store a form value in the session.
   *
   * Form values are always a string. This means an empty string is a valid
   * value for when a user wants to remove a value from the session. We have to
   * handle this special case for the session object.
   *
   * @param string $key
   *   The key.
   * @param string $value
   *   The value.
   */
  protected function setSessionValue($key, $value) {
    if (empty($value)) {

      // If the value is an empty string, remove the key from the session.
      $this->session
        ->remove($key);
    }
    else {
      $this->session
        ->set($key, $value);
    }
  }

  /**
   * {@inheritdoc}
   */
  public function submitForm(array &$form, FormStateInterface $form_state) {

    // We get the submitted form information and store it in the session. We use
    // key names which include our module name in order to avoid namespace
    // collision.
    $this
      ->setSessionValue('session_example.name', $form_state
      ->getValue('name'));
    $this
      ->setSessionValue('session_example.email', $form_state
      ->getValue('email'));
    $this
      ->setSessionValue('session_example.quest', $form_state
      ->getValue('quest'));
    $this
      ->setSessionValue('session_example.color', $form_state
      ->getValue('color'));

    // Tell the user what happened here, and that they can look at another page
    // to see the result.
    $this
      ->messenger()
      ->addMessage($this
      ->t('The session has been saved successfully. @link', [
      '@link' => Link::createFromRoute('Check here.', 'session_example.view')
        ->toString(),
    ]));

    // Since we might have changed the session information, we will invalidate
    // the cache tag for this session.
    $this
      ->invalidateCacheTag();
  }

  /**
   * Remove all the session information.
   */
  public function submitClearSession(array &$form, FormStateInterface $form_state) {
    $items = [
      'session_example.name',
      'session_example.email',
      'session_example.quest',
      'session_example.color',
    ];
    foreach ($items as $item) {
      $this->session
        ->remove($item);
    }
    $this
      ->messenger()
      ->addMessage($this
      ->t('Session is cleared.'));

    // Since we might have changed the session information, we will invalidate
    // the cache tag for this session.
    $this
      ->invalidateCacheTag();
  }

  /**
   * Invalidate the cache tag for this session.
   *
   * The form will use this method to invalidate the cache tag when the user
   * updates their information in the submit handlers.
   */
  protected function invalidateCacheTag() {
    $this->cacheTagInvalidator
      ->invalidateTags([
      'session_example:' . $this->session
        ->getId(),
    ]);
  }

}

Members

Namesort descending Modifiers Type Description Overrides
DependencySerializationTrait::$_entityStorages protected property An array of entity type IDs keyed by the property name of their storages.
DependencySerializationTrait::$_serviceIds protected property An array of service IDs keyed by property name used for serialization.
DependencySerializationTrait::__sleep public function 1
DependencySerializationTrait::__wakeup public function 2
FormBase::$configFactory protected property The config factory. 1
FormBase::$requestStack protected property The request stack. 1
FormBase::$routeMatch protected property The route match.
FormBase::config protected function Retrieves a configuration object.
FormBase::configFactory protected function Gets the config factory for this form. 1
FormBase::container private function Returns the service container.
FormBase::currentUser protected function Gets the current user.
FormBase::getRequest protected function Gets the request object.
FormBase::getRouteMatch protected function Gets the route match.
FormBase::logger protected function Gets the logger for a specific channel.
FormBase::redirect protected function Returns a redirect response object for the specified route. Overrides UrlGeneratorTrait::redirect
FormBase::resetConfigFactory public function Resets the configuration factory.
FormBase::setConfigFactory public function Sets the config factory for this form.
FormBase::setRequestStack public function Sets the request stack object to use.
FormBase::validateForm public function Form validation handler. Overrides FormInterface::validateForm 62
LinkGeneratorTrait::$linkGenerator protected property The link generator. 1
LinkGeneratorTrait::getLinkGenerator Deprecated protected function Returns the link generator.
LinkGeneratorTrait::l Deprecated protected function Renders a link to a route given a route name and its parameters.
LinkGeneratorTrait::setLinkGenerator Deprecated public function Sets the link generator service.
LoggerChannelTrait::$loggerFactory protected property The logger channel factory service.
LoggerChannelTrait::getLogger protected function Gets the logger for a specific channel.
LoggerChannelTrait::setLoggerFactory public function Injects the logger channel factory.
MessengerTrait::$messenger protected property The messenger. 29
MessengerTrait::messenger public function Gets the messenger. 29
MessengerTrait::setMessenger public function Sets the messenger.
RedirectDestinationTrait::$redirectDestination protected property The redirect destination service. 1
RedirectDestinationTrait::getDestinationArray protected function Prepares a 'destination' URL query parameter for use with \Drupal\Core\Url.
RedirectDestinationTrait::getRedirectDestination protected function Returns the redirect destination service.
RedirectDestinationTrait::setRedirectDestination public function Sets the redirect destination service.
SessionExampleForm::$cacheTagInvalidator protected property The cache tag invalidator service.
SessionExampleForm::$session protected property The session object.
SessionExampleForm::buildForm public function Form constructor. Overrides FormInterface::buildForm
SessionExampleForm::create public static function Instantiates a new instance of this class. Overrides FormBase::create
SessionExampleForm::getFormId public function Returns a unique string identifying the form. Overrides FormInterface::getFormId
SessionExampleForm::invalidateCacheTag protected function Invalidate the cache tag for this session.
SessionExampleForm::setSessionValue protected function Store a form value in the session.
SessionExampleForm::submitClearSession public function Remove all the session information.
SessionExampleForm::submitForm public function Form submission handler. Overrides FormInterface::submitForm
SessionExampleForm::__construct public function Constructs a new SessionExampleForm object.
StringTranslationTrait::$stringTranslation protected property The string translation service. 1
StringTranslationTrait::formatPlural protected function Formats a string containing a count of items.
StringTranslationTrait::getNumberOfPlurals protected function Returns the number of plurals supported by a given language.
StringTranslationTrait::getStringTranslation protected function Gets the string translation service.
StringTranslationTrait::setStringTranslation public function Sets the string translation service to use. 2
StringTranslationTrait::t protected function Translates a string to the current language or to a given language.
UrlGeneratorTrait::$urlGenerator protected property The url generator.
UrlGeneratorTrait::getUrlGenerator Deprecated protected function Returns the URL generator service.
UrlGeneratorTrait::setUrlGenerator Deprecated public function Sets the URL generator service.
UrlGeneratorTrait::url Deprecated protected function Generates a URL or path for a specific route based on the given parameters.