How can I update existing config from a custom module's config/install yamls?

Question

I added some config yml files to my module's config/install directory so that it is installed directly when installing my module, it works well only if there isn't a config file with the same name installed already and only if it's the first install. So my question is there a way to update the config files already installed with my module's config file, and delete them when uninstalling the module ?

Answer 1

A module install should not update config. If you want to update existing config, your module should implement hook_update_N() (see docs) instead.

However, you could add a dependencies: enforced section to your YML config files. This will remove your existing config on module uninstall, and install the newest config on module reinstall. This way you can "emulate" a simple update mechanism for your own, private custom module. See doc for enforced config dependencies

Answer 2

You can update custom config with a settings form you build. In a custom module custom_mailing add a file called custom_mailing.routing.yml add the following route:

custom_mailing.route_admin_settings:
  path: '/admin/config/mailing'
  defaults:
    _title: 'Custom mailing'
    _form: '\Drupal\custom_mailing\Form\AdminSettingsForm'
  requirements:
    _permission: 'administer custom_mailing settings'

Now I want a boolean value to be editable. I create a file in a map config/install called custom_mailings.settings.yml with the following content:

mailsettings:
  enabled: 0

In a module called custom_mailing. Inside src/Form add file called AdminSettingsForm.php.

<?php

namespace Drupal\custom_mailing\Form;

use Drupal\Core\Form\ConfigFormBase;
use Drupal\Core\Form\FormStateInterface;

/**
 * Class AdminSettingsForm.
 *
 * @package Drupal\custom_mailing\Form
 */
class AdminSettingsForm extends ConfigFormBase {

  /**
   * {@inheritdoc}
   */
  public function getFormId() {
    return 'custom_mailing_admin_settings_form';
  }

  /**
   * {@inheritdoc}
   */
  protected function getEditableConfigNames() {
    return [
      'custom_mailing.settings',
    ];
  }

  /**
   * {@inheritdoc}
   */
  public function buildForm(array $form, FormStateInterface $form_state) {
    $config = $this->config('custom_mailing.settings');

    $form['mailsettings'] = [
      '#tree' => TRUE,
      '#type' => 'fieldset',
      '#title' => $this->t('Email settings'),
    ];

    $form['mailsettings']['enabled'] = [
      '#type' => 'checkbox',
      '#title' => $this->t('Enable sending of e-mails.'),
      '#default_value' => $config->get('mailsettings.enabled'),
    ];

    return parent::buildForm($form, $form_state);
  }

  /**
   * {@inheritdoc}
   */
  public function submitForm(array &$form, FormStateInterface $form_state) {
    $config = $this->config('custom_mailing.settings');
    $config->set('mailsettings', $form_state->getValue('mailsettings'));
    $config->save();
    parent::submitForm($form, $form_state);
  }

}