Changing configuration using form

Question

I have created a form using which I want to make changes in the configuration.Currently I am submitting form doing something like this:

 public function submitForm(array &$form, FormStateInterface $form_state) {
  \Drupal::service('config.factory')
    ->getEditable('module.settings')
    ->set('module_entities', $form_state->getValue('module_entities'))
    ->save();
 }

But the problem is when I have submitted the form changes in the configuration are not reflected.But when I clear the cache after submitting the form the changes are reflected.what changes should I make so that when user submits form the changes are reflected thereafter?

Update: I tried to find my mistake and found out that configuration is getting updated but somehow the changes getting lost and not being reflected in the block which I have created. In the block creation code I am creating blocks for different entities depending on the entities present in the configuration.But the configuration is not showing correct values so block for required entities is not being created.Surprisingly when I clear cache the code works(which means configuration becomes updated).Does this mean for block creation I need to clear cache? I am currently using this code:

 `public function getDerivativeDefinitions($base_plugin_definition) {
   $this->derivatives[$entity_type] = $base_plugin_definition;
   $this->derivatives[$entity_type]['admin_label'] .= ' (' . $entity_definition->getLabel() .')';
   $this->derivatives[$entity_type]['cache'] = ?;

}`

What should I add over here to make block depend on configuration without clearing cache? In the plugin I am returning:

public function build() { return array( '#theme' => 'links__entity__module', '#links' => $this->linkBuilder->buildLinks($this->request->attributes->get($entity_type)), ); }

Answer 1

Blocks are cached by default.

You don't need to manually clear those caches when you change your configuration, but you need to flag/tag your blocks output to tell Drupal that your block output depends on your configuration.

Read the Cacheability documentation. What you need is something like this:

$output['#cache']['tags'] = $config->getCacheTags();

Answer 2

Something which I did in my form was:

    public function submitForm(array &$form, FormStateInterface $form_state) {
        $config = \Drupal::configFactory()->getEditable('module.settings');
        $userInputValues = $form_state->getUserInput();

        $config
            ->set('module_entities', $userInputValues('module_entities'))
            ->save();
        parent::submitForm($form, $form_state);
    }