Provides methods to manage form state values. Hierarchy trait \Drupal\Core\Form\

public FormStateInterface::prepareCallback($callback)

If set to TRUE the form will NOT perform a redirect, even if self::$redirect is set. This property is uncacheable.

public FormStateInterface::setMethod($method)

The CSRF token generator to validate the form token. Type:

Defines the behavior a confirmation form. Hierarchy interface \Drupal\Core\Form\

public SubformState::setErrorByName($name, $message = '')

The form state. Type:

public FormStateInterface::setTemporaryValue($key, $value)

public FormStateDecoratorBase::hasFileElement()