public static function getSlug($model)
    {
        $i18nModels = $model->i18n;
        $slugs = [];
        foreach ($i18nModels as $i18nModel) {
            if (empty($i18nModel->body)) continue; // skip languages for news without body
            $slugs[$i18nModel->lang_code] = $i18nModel->slug;
        }

        //$langs = array_keys(LangHelper::activeLanguages()); // better use as container-module's member:
        $module = Module::getModuleByClassname(Module::className());
        $langHelper = $module->langHelper;
        $langs = array_keys($langHelper::activeLanguages());
        $slug = '';
        foreach ($langs as $lang) {
            if (!empty($slugs[$lang])) {
                $slug = $slugs[$lang];
                break;
            }
        }
        if (strlen($slug) > static::$slugMaxLen) {
            $slug = substr($slug, 0, static::$slugMaxLen);
        }
        $slug = trim($slug, '-');
        return $slug;
    }