public function buildRules(RulesChecker $rules)
    {
        return $rules->add($rules->existsIn(['category_id'], 'Categories', I18N_SELECT_VALID_OPTION))
            ->add($rules->existsIn(['user_id'], 'Users', I18N_SELECT_VALID_OPTION))
            ->add($rules->isUnique(['slug'], I18N_VALUE_ALREADY_USED))
            ->add($rules->isUnique(['title'], I18N_VALUE_ALREADY_USED));
    }