'textfield', '#title' => $this->t('Example'), '#default_value' => $this->config('{{ machine_name }}.settings')->get('example'), ]; return parent::buildForm($form, $form_state); } /** * {@inheritdoc} */ public function validateForm(array &$form, FormStateInterface $form_state): void { // @todo Validate the form here. // Example: // @code // if ($form_state->getValue('example') === 'wrong') { // $form_state->setErrorByName( // 'message', // $this->t('The value is not correct.'), // ); // } // @endcode parent::validateForm($form, $form_state); } /** * {@inheritdoc} */ public function submitForm(array &$form, FormStateInterface $form_state): void { $this->config('{{ machine_name }}.settings') ->set('example', $form_state->getValue('example')) ->save(); parent::submitForm($form, $form_state); } }