MessageCommand.php

<?php

namespace Drupal\Core\Ajax;

use Drupal\Core\Asset\AttachedAssets;

/**
 * AJAX command for a JavaScript Drupal.message() call.
 *
 * Developers should be extra careful if this command and
 * \Drupal\Core\Ajax\AnnounceCommand are included in the same response. Unless
 * the `announce` option is set to an empty string (''), this command will
 * result in the message being announced to screen readers. When combined with
 * AnnounceCommand, this may result in unexpected behavior. Manual testing with
 * a screen reader is strongly recommended.
 *
 * Here are examples of how to suppress announcements:
 * @code
 *   $command = new MessageCommand("I won't be announced", NULL, [
 *     'announce' => '',
 *   ]);
 * @endcode
 *
 * @see \Drupal\Core\Ajax\AnnounceCommand
 *
 * @ingroup ajax
 */
class MessageCommand implements CommandInterface, CommandWithAttachedAssetsInterface {
    
    /**
     * The message text.
     *
     * @var string
     */
    protected $message;
    
    /**
     * Whether to clear previous messages.
     *
     * @var bool
     */
    protected $clearPrevious;
    
    /**
     * The query selector for the element the message will appear in.
     *
     * @var string
     */
    protected $wrapperQuerySelector;
    
    /**
     * The options passed to Drupal.message().add().
     *
     * @var array
     */
    protected $options;
    
    /**
     * Constructs a MessageCommand object.
     *
     * @param string $message
     *   The text of the message.
     * @param string|null $wrapper_query_selector
     *   The query selector of the element to display messages in when they
     *   should be displayed somewhere other than the default.
     *   @see Drupal.Message.defaultWrapper()
     * @param array $options
     *   The options passed to Drupal.message().add().
     * @param bool $clear_previous
     *   If TRUE, previous messages will be cleared first.
     */
    public function __construct($message, $wrapper_query_selector = NULL, array $options = [], $clear_previous = TRUE) {
        $this->message = $message;
        $this->wrapperQuerySelector = $wrapper_query_selector;
        $this->options = $options;
        $this->clearPrevious = $clear_previous;
    }
    
    /**
     * {@inheritdoc}
     */
    public function render() {
        return [
            'command' => 'message',
            'message' => $this->message,
            'messageWrapperQuerySelector' => $this->wrapperQuerySelector,
            'messageOptions' => $this->options,
            'clearPrevious' => $this->clearPrevious,
        ];
    }
    
    /**
     * {@inheritdoc}
     */
    public function getAttachedAssets() {
        $assets = new AttachedAssets();
        $assets->setLibraries([
            'core/drupal.message',
        ]);
        return $assets;
    }

}