How should I get the user submitted input?

Question

On an submission handler, should I fetch the user input via \Drupal::request()->request->get() or is $form_state->getValues(); the better (more saver) way?

Answer 1

$request->request->all() != $form_state->getValues()

$request->request->all() === $_POST
$request->query->all() === $_GET

See in Drupal\Core\Form\FormBuilder::buildForm()

$input = $form_state->isMethodType('get') ? $request->query->all() : $request->request->all();
$form_state->setUserInput($input);

$form_state->getValues() is already modified data that is formed on the basis of $form_state['input'] and #default_value

See in Drupal\Core\Form\FormBuilder::handleInputElement();

Pay attention to #value_callback it forms the value of the field

Answer 2

Not entirely sure what you're doing, but the answer is probably $form_state->getValues() or $form_state->getValue(). There is also $form_state->getUserInput(), but as you'll see on that page, it recommends you use one of the first 2 options unless you have a specific reason and know what you're doing.