function FormBuilder::retrieveForm

Overrides FormBuilderInterface::retrieveForm

File

core/lib/Drupal/Core/Form/FormBuilder.php, line 501

Class

FormBuilder

Provides form building and processing.

Namespace

Code

public function retrieveForm($form_id, FormStateInterface &$form_state) {
    // Record the $form_id.
    $form_state->addBuildInfo('form_id', $form_id);
    // We save two copies of the incoming arguments: one for modules to use
    // when mapping form ids to constructor functions, and another to pass to
    // the constructor function itself.
    $build_info = $form_state->getBuildInfo();
    $args = $build_info['args'];
    $callback = [
        $form_state->getFormObject(),
        'buildForm',
    ];
    $form = [];
    // Assign a default CSS class name based on $form_id.
    // This happens here and not in self::prepareForm() in order to allow the
    // form constructor function to override or remove the default class.
    $form['#attributes']['class'][] = Html::getClass($form_id);
    // Same for the base form ID, if any.
    if (isset($build_info['base_form_id'])) {
        $form['#attributes']['class'][] = Html::getClass($build_info['base_form_id']);
    }
    // We need to pass $form_state by reference in order for forms to modify it,
    // since call_user_func_array() requires that referenced variables are
    // passed explicitly.
    $args = array_merge([
        $form,
        &$form_state,
    ], $args);
    $form = call_user_func_array($callback, $args);
    // If the form returns a response, skip subsequent page construction by
    // throwing an exception.
    // @see Drupal\Core\EventSubscriber\EnforcedFormResponseSubscriber
    //
    // @todo Exceptions should not be used for code flow control. However, the
    //   Form API currently allows any form builder functions to return a
    //   response.
    //   @see https://www.drupal.org/node/2363189
    if ($form instanceof Response) {
        throw new EnforcedResponseException($form);
    }
    $form['#form_id'] = $form_id;
    return $form;
}