Drupal 8 : Get a config settings value being stored in blocs

Question

I have create a block with a form and stored something i called 'submit_action_amu_dud_form_block_settings'

 public function blockSubmit($form, FormStateInterface $form_state) {

    $this->configuration['submit_action_amu_dud_form_block_settings'] = $form_state->getValue('submit_action_amu_dud_form_block_settings');

 }

in a method of the same class i can retrieve the value

      $config = $this->getConfiguration();
      $my_stored value=$config['submit_action_amu_dud_form_block_settings']

how can i get it from . module hook_form_alter callback ?

    function mymodule_form_alter(&$form, \Drupal\Core\Form\FormStateInterface $form_state, $form_id) {


if ($form_id == 'amu_dud_form') {
    $form['actions']['submit']['#submit'][] = 'my_submit_method';        
}
}

 function my_submit_method(&$form, \Drupal\Core\Form\FormStateInterface $form_state, $form_id) {

//$my_stored_value=??

Answer 1

You need to load the block if your outside of the class, for that you need it's id.

$block = \Drupal\block\Entity\Block::load($bid);
$my_stored_value = $block->get('settings')['submit_action_amu_dud_form_block_settings'];

The id can be found in it's annotation if it's custom: @Block( * id = "my_fancy_block_id". If there are several instances of the block this may be altered and can be looked up in the DB, or the block config admin section - check the urls there.

Answer 2

thanks to remy i have been able to retrieve the value from an instance of block this way:

//instance of block bid found in db
$block = \Drupal\block\Entity\Block::load('my_blockinstance_bid');
$block_settings = $block->get('settings');
$url=$block_settings['my_stored_setting'];

The problem remain then , when having mutliple instance of blocs, to load a block config dynamically corresponding to the settings value that have been stored for the block being displayed on the page ?