Вывод ключей

class City extends Area
{
 
    /**
     * @param string $type
     * @return string
     */
    public static function key($type = '')
    {
        return parent::_key(self::KEY_CITY, $type);
    }
 
    /**
     * @return void
     */
    public static function ajaxGetCitiesByNameSuggestion()
    {
        $areaRef = ArrayHelper::getValue($_POST, 'parent_area_ref', null);
        $name = $_POST['name'];
        if(is_null($areaRef)){
            $areas = self::findByNameSuggestion($name);
        }else{
            $areas = self::findByNameSuggestionAndParentArea($name, $areaRef);
        }
        foreach ($areas as $area) {
            $area->getRef();
            $area->getDescription();
        }
        echo json_encode($areas);
        exit;
    }
}

private function addNovaPoshtaFields($fields, $location)
    {
        /** @noinspection PhpUndefinedFieldInspection */
        $area = WC()->customer->nova_poshta_region;
        /** @noinspection PhpUndefinedFieldInspection */
        $city = WC()->customer->nova_poshta_city;
        $required = NP()->isGet() ?: (NP()->isNP() && NP()->isCheckout());
        $fields[Region::key($location)] = [
            'label' => __('Region', NOVA_POSHTA_DOMAIN),
            'type' => 'select',
            'required' => $required,
            'default' => '',
            'options' => OptionsHelper::getList(Region::findAll()),
            'class' => array(),
            'custom_attributes' => array(),
        ];
        $fields[City::key($location)] = [
            'label' => __('City', NOVA_POSHTA_DOMAIN),
            'type' => 'select',
            'required' => $required,
            'options' => OptionsHelper::getList(City::findByParentAreaRef($area)),
            'class' => array(),
            'value' => '',
            'custom_attributes' => array(),
        ];
        $fields[Warehouse::key($location)] = [
            'label' => __('Nova Poshta Warehouse (#)', NOVA_POSHTA_DOMAIN),
            'type' => 'select',
            'required' => $required,
            'options' => OptionsHelper::getList(Warehouse::findByParentAreaRef($city)),
            'class' => array(),
            'value' => '',
            'custom_attributes' => array(),
        ];
        return $fields;
    }

        foreach ($locations as $location) {
            $result[$location->ref] = $location->description;
        }

        foreach ($locations as $location) {
            $result[$location->description] = $location->description;
        }

    public static function getList2($locations, $enableEmpty = true)
    {
        $result = array();
        if ($enableEmpty) {
            $result[''] = __('Choose an option', NOVA_POSHTA_DOMAIN);
        }
        foreach ($locations as $location) {
            $result[$location->description] = $location->description;
        }
        return $result;
    }

private function createTableAreas()
    {
        $table = Area::table();
        $region = Area::KEY_REGION;
        $city = Area::KEY_CITY;
        $warehouse = Area::KEY_WAREHOUSE;
 
        // http://stackoverflow.com/questions/766809/whats-the-difference-between-utf8-general-ci-and-utf8-unicode-ci
        $tableOptions = 'CHARACTER SET utf8 COLLATE utf8_unicode_ci ENGINE=InnoDB';
 
        $query = <<<QUERY
            CREATE TABLE IF NOT EXISTS {$table} (
                `id` INT(10) UNSIGNED NOT NULL AUTO_INCREMENT,
                `ref` VARCHAR(50) NOT NULL,
                `area_type` ENUM('$region','$city','$warehouse') NOT NULL,
                `description` TINYTEXT NOT NULL,
                `description_ru` TINYTEXT,
                `parent_area_ref` VARCHAR(50) DEFAULT NULL,
                `updated_at` INT(10) UNSIGNED NOT NULL,
                `created_at` TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
                PRIMARY KEY `id` (`id`),
                UNIQUE KEY `uk_ref` (`ref`)
            ){$tableOptions}
QUERY;
        $this->db->query($query);
    }