roblib_lac.module

<?php

/**
 * @file
 * Primary module hooks for roblib_lac module.
 */

use Drupal\Core\Form\FormStateInterface;

/**
 * Implements hook_form_form_id_alter().
 */
function roblib_lac_form_rest_oai_pmh_settings_form_alter(&$form, FormStateInterface $form_state, $form_id) {
  $config = \Drupal::configFactory()->getEditable('rest_oai_pmh.settings');

  $view = $config->get('lac_view');
  $new_element = [
    'lac_view' => [
      '#type' => 'details',
      '#tree' => TRUE,
      '#open' => TRUE,
      '#title' => t('LAC View'),
      '#attributes' => ['style' => 'max-width: 750px'],
      '#description' => t('<p>Set which view to pull information from for the lac mapping.</p>'),
      'view_machine_name' => [
        '#type' => 'textfield',
        '#title' => t('View Machine Name'),
        '#default_value' => empty($view['view_machine_name']) ? '' : $view['view_machine_name'],
      ],
      'view_display_name' => [
        '#type' => 'textfield',
        '#title' => ('View Display Name'),
        '#default_value' => empty($view['view_display_name']) ? '' : $view['view_display_name'],
      ],
    ],
  ];

  $form = array_merge(
    array_slice($form, 0, array_search('repository_name', array_keys($form)), TRUE),
    ['lac_view' => $new_element],
    array_slice($form, array_search('repository_name', array_keys($form)), NULL, TRUE)
  );
  $form['actions']['submit']['#submit'][] = 'roblib_lac_rest_oai_admin_settings_submit';

}

/**
 * Saves additional configs.
 */
function roblib_lac_rest_oai_admin_settings_submit(array &$form, $form_state) {
  $value = $form_state->getValue('lac_view');
  \Drupal::configFactory()->getEditable('rest_oai_pmh.settings')
    ->set('lac_view', $form_state->getValue('lac_view'))
    ->save();
}