class Simplest in Examples for Developers 3.x

A relatively simple AJAX demonstration form.

Hierarchy

• class \Drupal\Core\Form\FormBase implements ContainerInjectionInterface, FormInterface uses DependencySerializationTrait, LoggerChannelTrait, MessengerTrait, RedirectDestinationTrait, StringTranslationTrait
  • class \Drupal\ajax_example\Form\Simplest

1 string reference to 'Simplest'

ajax_example.routing.yml in modules/ajax_example/ajax_example.routing.yml

modules/ajax_example/ajax_example.routing.yml

File

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

Namespace

Drupal\ajax_example\Form

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

Name	Modifiers	Type	Description	Overrides
DependencySerializationTrait::$_entityStorages	protected	property
DependencySerializationTrait::$_serviceIds	protected	property
DependencySerializationTrait::__sleep	public	function		2
DependencySerializationTrait::__wakeup	public	function		2
FormBase::$configFactory	protected	property	The config factory.	3
FormBase::$requestStack	protected	property	The request stack.	1
FormBase::$routeMatch	protected	property	The route match.
FormBase::config	protected	function	Retrieves a configuration object.
FormBase::configFactory	protected	function	Gets the config factory for this form.	3
FormBase::container	private	function	Returns the service container.
FormBase::create	public static	function	Instantiates a new instance of this class. Overrides ContainerInjectionInterface::create	105
FormBase::currentUser	protected	function	Gets the current user.
FormBase::getRequest	protected	function	Gets the request object.
FormBase::getRouteMatch	protected	function	Gets the route match.
FormBase::logger	protected	function	Gets the logger for a specific channel.
FormBase::redirect	protected	function	Returns a redirect response object for the specified route.
FormBase::resetConfigFactory	public	function	Resets the configuration factory.
FormBase::setConfigFactory	public	function	Sets the config factory for this form.
FormBase::setRequestStack	public	function	Sets the request stack object to use.
FormBase::validateForm	public	function	Form validation handler. Overrides FormInterface::validateForm	72
LoggerChannelTrait::$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::$messenger	protected	property	The messenger.	27
MessengerTrait::messenger	public	function	Gets the messenger.	27
MessengerTrait::setMessenger	public	function	Sets the messenger.
RedirectDestinationTrait::$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.	4
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.