How can I programmatically change a system message?

Question

I want to change or hide a message shown from the CommentForm class.

In my entity_insert() hook I either unset $_SESSION['messages'] and add a new message or call drupal_get_message($type, TRUE).

The problem is that the new message will be set before the one I want to change; if I unset the message array, the new message will be gone too.

I also tried to hook in the specific form and add a submission handler, but that doesn't work.

/**
 * Implements hook_form_FORM_ID_alter().
 */
function my_module_form_comment_form_alter(&$form, FormStateInterface $form_state) {
  $form['actions']['submit']['#submit'][]  = 'my_module_comment_form_submit';
}

/**
 * Submit handler.
 */
function my_module_comment_form_submit(&$form, FormStateInterface $form_state) {
  $message = $_SESSION['messages'];
}

How can I programmatically change a system message?

Answer 1

System messages are stored in a Symfony Flashbag, so there is no need to hack session variables, which can change from version to version. In Drupal 8.5 a new Messenger service was introduced to encapsulate the symfony flash bag and you can delete messages with deleteAll():

\Drupal::messenger()->deleteAll();

Answer 2

I was seeking a similar solution. I found How can I remove a message shown from a different module? which show how to achieve it using hook_preprocess_status_messages().

/**
 * Implements hook_preprocess_HOOK().
 *
 * @param $variables
 */
function mymodule_preprocess_status_messages(&$variables) {
  if(isset($variables['message_list']['status'])){
    $status_messages = $variables['message_list']['status'];
    foreach($status_messages as $delta => $message) {
      if (strpos((string) $message, 'The message that I am expecting') !== FALSE) {
        $variables['message_list']['status'][$delta] = "Some different message text";
      }
    }
  }
}

Answer 3

I think the answer might be not to use hook_entity_insert(). By that time, it is too late: the content has already been created, so the system will create the message accordingly.

As the hook_entity_insert documentation says: hook_entity_insert responds to the creation of a new entity.

Maybe try another hook from the Entity API, one that does not cause the unwanted message to be generated.

Answer 4

Drupal 8 delete message:

/**
 * Deletes status message after user registration.
 */
function YOURMODULE_user_register_form_submit($form, &$form_state) {
  $messenger = \Drupal::messenger();
  $messenger->deleteByType('status');
}

/**
 * Implements hook_form_alter().
 */
function YOURMODULE_form_alter(&$form, \Drupal\Core\Form\FormStateInterface $form_state, $form_id) {
  switch ($form_id) {
    case 'user_register_form':
      $form['actions']['submit']['#submit'][] = 'forms_opm_user_register_form_submit';
      break;
  }
}

Answer 5

Assuming the messages in question are form_errors from validation of the form:

Rather than altering the messages after the fact you could override/replace the #validate function(s) that produce the errors in the first place (from hook_form_alter) and provide your own custom errors.

Answer 6

/**
 * Implements hook_preprocess_HOOK().
 */
function comment_limit_preprocess_node(&$variables) {
  if (in_array('node-max', $_SESSION['messages']['status']) && in_array('user-max', $_SESSION['messages']['status'])) {
    drupal_get_messages('status', TRUE);
    drupal_set_message(t('The comment limit for this node has been reached!'));
    drupal_set_message(t('Your comment limit has been reached!'));
  }
  elseif (in_array('node-max', $_SESSION['messages']['status'])) {
    drupal_get_messages('status', TRUE);
    drupal_set_message(t('The comment limit for this node has been reached!'));
  }
  elseif (in_array('user-max', $_SESSION['messages']['status'])) {
    drupal_get_messages('status', TRUE);
    drupal_set_message(t('Your comment limit has been reached!'));
  }
}

This looks a little prettier and it works.

Answer 7

You can do unset($SESSION['_symfony_flashes']['status'][0]). In my case, unset($_SESSION['messages']['status']) didn't work. Then I was able to do \Drupal::messenger()->addMessage(t('My message here')).

Hope this helps someone.