PathFormBase::buildForm

public PathFormBase::buildForm(array $form, FormStateInterface $form_state, $pid = NULL)

public function buildForm(array $form, FormStateInterface $form_state, $pid = NULL) {
  $this->path = $this->buildPath($pid);
  $form['source'] = array(
    '#type' => 'textfield',
    '#title' => $this->t('Existing system path'),
    '#default_value' => $this->path['source'],
    '#maxlength' => 255,
    '#size' => 45,
    '#description' => $this->t('Specify the existing path you wish to alias. For example: /node/28, /forum/1, /taxonomy/term/1.'),
    '#field_prefix' => $this->requestContext->getCompleteBaseUrl(),
    '#required' => TRUE,
  );
  $form['alias'] = array(
    '#type' => 'textfield',
    '#title' => $this->t('Path alias'),
    '#default_value' => $this->path['alias'],
    '#maxlength' => 255,
    '#size' => 45,
    '#description' => $this->t('Specify an alternative path by which this data can be accessed. For example, type "/about" when writing an about page.'),
    '#field_prefix' => $this->requestContext->getCompleteBaseUrl(),
    '#required' => TRUE,
  );

  // A hidden value unless language.module is enabled.
  if (\Drupal::moduleHandler()->moduleExists('language')) {
    $languages = \Drupal::languageManager()->getLanguages();
    $language_options = array();
    foreach ($languages as $langcode => $language) {
      $language_options[$langcode] = $language->getName();
    }

    $form['langcode'] = array(
      '#type' => 'select',
      '#title' => $this->t('Language'),
      '#options' => $language_options,
      '#empty_value' => LanguageInterface::LANGCODE_NOT_SPECIFIED,
      '#empty_option' => $this->t('- None -'),
      '#default_value' => $this->path['langcode'],
      '#weight' => -10,
      '#description' => $this->t('A path alias set for a specific language will always be used when displaying this page in that language, and takes precedence over path aliases set as <em>- None -</em>.'),
    );
  }
  else {
    $form['langcode'] = array(
      '#type' => 'value',
      '#value' => $this->path['langcode']
    );
  }

  $form['actions'] = array('#type' => 'actions');
  $form['actions']['submit'] = array(
    '#type' => 'submit',
    '#value' => $this->t('Save'),
    '#button_type' => 'primary',
  );

  return $form;
}