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class Simplest in Examples for Developers 8

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

A relatively simple AJAX demonstration form.

Hierarchy

Expanded class hierarchy of Simplest

1 string reference to 'Simplest'
ajax_example.routing.yml in ajax_example/ajax_example.routing.yml
ajax_example/ajax_example.routing.yml

File

ajax_example/src/Form/Simplest.php, line 11

Namespace

Drupal\ajax_example\Form
View source
class Simplest extends FormBase {

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

  /**
   * {@inheritdoc}
   */
  public function buildForm(array $form, FormStateInterface $form_state) {
    $form['changethis'] = [
      '#title' => $this
        ->t("Choose something and explain why"),
      '#type' => 'select',
      '#options' => [
        'one' => 'one',
        'two' => 'two',
        'three' => 'three',
      ],
      '#ajax' => [
        // #ajax has two required keys: callback and wrapper.
        // 'callback' is a function that will be called when this element
        // changes.
        'callback' => '::promptCallback',
        // 'wrapper' is the HTML id of the page element that will be replaced.
        'wrapper' => 'replace-textfield-container',
      ],
    ];

    // The 'replace-textfield-container' container will be replaced whenever
    // 'changethis' is updated.
    $form['replace_textfield_container'] = [
      '#type' => 'container',
      '#attributes' => [
        'id' => 'replace-textfield-container',
      ],
    ];
    $form['replace_textfield_container']['replace_textfield'] = [
      '#type' => 'textfield',
      '#title' => $this
        ->t("Why"),
    ];

    // An AJAX request calls the form builder function for every change.
    // We can change how we build the form based on $form_state.
    $value = $form_state
      ->getValue('changethis');

    // The getValue() method returns NULL by default if the form element does
    // not exist. It won't exist yet if we're building it for the first time.
    if ($value !== NULL) {
      $form['replace_textfield_container']['replace_textfield']['#description'] = $this
        ->t("Say why you chose '@value'", [
        '@value' => $value,
      ]);
    }
    return $form;
  }

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

    // No-op. Our form doesn't need a submit handler, because the form is never
    // submitted. We add the method here so we fulfill FormInterface.
  }

  /**
   * Handles switching the available regions based on the selected theme.
   */
  public function promptCallback($form, FormStateInterface $form_state) {
    return $form['replace_textfield_container'];
  }

}

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::$routeMatch protected property The route match.
FormBase::config protected function Retrieves a configuration object.
FormBase::configFactory protected function Gets the config factory for this form. 1
FormBase::container private function Returns the service container.
FormBase::create public static function Instantiates a new instance of this class. Overrides ContainerInjectionInterface::create 87
FormBase::currentUser protected function Gets the current user.
FormBase::getRequest protected function Gets the request object.
FormBase::getRouteMatch protected function Gets the route match.
FormBase::logger protected function Gets the logger for a specific channel.
FormBase::redirect protected function Returns a redirect response object for the specified route. Overrides UrlGeneratorTrait::redirect
FormBase::resetConfigFactory public function Resets the configuration factory.
FormBase::setConfigFactory public function Sets the config factory for this form.
FormBase::setRequestStack public function Sets the request stack object to use.
FormBase::validateForm public function Form validation handler. Overrides FormInterface::validateForm 62
LinkGeneratorTrait::$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::$redirectDestination protected property The redirect destination service. 1
RedirectDestinationTrait::getDestinationArray protected function Prepares a 'destination' URL query parameter for use with \Drupal\Core\Url.
RedirectDestinationTrait::getRedirectDestination protected function Returns the redirect destination service.
RedirectDestinationTrait::setRedirectDestination public function Sets the redirect destination service.
Simplest::buildForm public function Form constructor. Overrides FormInterface::buildForm
Simplest::getFormId public function Returns a unique string identifying the form. Overrides FormInterface::getFormId
Simplest::promptCallback public function Handles switching the available regions based on the selected theme.
Simplest::submitForm public function Form submission handler. Overrides FormInterface::submitForm
StringTranslationTrait::$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.