How do I access the parameters fields of hook_mail_alter(&$message)?

Question

I am using hook_mail_alter in drupal 8 to alter the email messages sent through contact form . How can I access $message['params'] fields in hook_mail_alter()?

I am getting the following values with print_r(array_keys($message['params']));.

Array (
  [0] => contact_message
  [1] => sender
  [2] => contact_form
)

Can anyone suggest how I access the contact form fields?

When I access the values with print_r($message['params']['contact_form']);die; I don't get anything displayed.

Answer 1

The message entity is stored in $message['params']['contact_message'] and it contains all the values from the contact form. Given that it's an entity of type contact_message, you can operate with get() method to get the values of any field that your contact message might have. Example:

/**
 * Implements hook_mail_alter().
 */
function mymodule_mail_alter(&$message) {
  if (isset($message['id']) && $message['id'] == 'contact_page_mail') {
    /** @var \Drupal\contact\Entity\Message $contact_message */
    $contact_message = $message['params']['contact_message'];
    // Get sender's name.
    $sender_name = $contact_message->getSenderName();
    // Get sender's mail.
    $sender_mail = $contact_message->getSenderMail();
    // Get subject.
    $subject = $contact_message->getSubject();
    // Get message.
    $message_body = $contact_message->getMessage();
    // Get the value of "field_request" field.
    $request_value = $contact_message->get('field_request')->getValue();
  }
}

Answer 2

The original post assumes the use of the "Contact" module, but for a more generic solution (for example, for user account registration/activation emails), you can access user account information via the 'account' element:

/**
 * Implements hook_mail_alter().
 *
 * Modify outgoing emails.
 */
function mymodule_mail_alter(&$message) {
  switch ($message['id']) {
    case 'user_register_pending_approval':
      $field_data = $message['params']['account']->get('field_example')->getValue();
      // do something with $field_data in $message['body']
      break;

    case 'user_status_activated':
      if ($message['params']['account']->hasRole('content_editor')) {
        // do something with $field_data in $message['body']
      }
      break;
  }
}