Missing form state values after adding submit function

Question

I added a submit function in the form_alter hook when inserting a node:

$form['actions']['save_as_draft'] = [
  '#type' => 'submit',
  '#value' => t('Save as Draft'),
  '#submit' => ['save_as_draft'],
  '#limit_validation_errors' => [],
];

In the save_as_draft() function, I want to get the address value from the form state, but there are no values (except for the additional submit button).

function save_as_draft(&$form, Drupal\Core\Form\FormStateInterface $form_state) {
  var_dump($form_state->getValue('field_address'));                      // outputs NULL
  var_dump($form_state->get('field_address'));                           // outputs NULL 
  var_dump($form['field_address']['widget'][0]['value']['#value']);      // outputs 'Address value'
  var_dump(array_keys($form_state->getValues())); // outputs { [0]=>  "save_as_draft" [1]=> "op" }
}

How can I get the form_state values in this alternative submit function without validating the whole form?

Is there another way of retrieving the form values instead of digging through the widget arrays?

Answer 1

Entity forms usually run as first submit handler the entity builder functions. Then following submit handlers can get the processed field values directly from the form object entity:

$entity = $form_state->getFormObject()->getEntity();
$field_values = $entity->field_foo->getValue();

Answer 2

the correct $form_state get value should be

*recommended* : $form_state->getValue('key'); 
or
$form_state->getValues()['key']

Answer 3

How can I get the form_state values in this alternative submit function without validating the whole form?

$form['actions']['save_as_draft'] = [
  '#type' => 'submit',
  '#value' => t('Save as Draft'),
  '#submit' => ['::submitForm', '::save'],
];
array_unshift($form['#validate'], 'save_as_draft'); // adds a custom validate that runs before the default node validate.

Now this should work

function save_as_draft(&$form, Drupal\Core\Form\FormStateInterface $form_state) {
  if ($form_state->getTriggeringElement()['#parents'][0] == 'save_as_draft') { // check Save As Draft button was clicked
    var_dump($form_state->getValue('field_address')); 
  }
}