Extend Woocommerce Widget Class - WC_Widget_Product_Categories

Question

I'm trying to extend the woocommerce class used to create the product categories widget in my own plugin which adds a new taxonomy for woo commerce products called "departments".

When I extend WP_Widget everything works just fine and I see a new widget that I can add in Appearance->Widgets. However, when I'm trying to extend WC_Widget or WC_Widget_Product_Categories I simply don't see a new widget, even though I'm not getting any php errors.

Here's what I have which doesn't work:

//get the base classes
if(!class_exists('WC_Widget_Product_Categories')) {
    require_once ABSPATH . 'wp-content/plugins/woocommerce/includes/abstracts/abstract-wc-widget.php';
    require_once ABSPATH . 'wp-content/plugins/woocommerce/includes/widgets/class-wc-widget-product-categories.php';
}

/**
 * Product departments widget class.
 *
 * @extends WC_Widget_Product_Categories
 */
class WC_Widget_Product_Departments extends WC_Widget_Product_Categories {
    /**
     * Constructor.
     */
    public function __construct() {
        $this->widget_cssclass    = 'woocommerce widget_product_departments';
        $this->widget_description = __( 'A list or dropdown of product departments.', 'woocommerce' );
        $this->widget_id          = 'woocommerce_product_departments';
        $this->widget_name        = __( 'Shop Departments', 'woocommerce' );

        parent::__construct();
    }
}

and in my main plugin file:

add_action( 'widgets_init', 'register_department_widgets', 15 );

function register_department_widgets() {
  register_widget( 'WC_Widget_Product_Departments' );
}

However, if I change the class being extended it does work:

class WC_Widget_Product_Departments extends WC_Widget

What am I doing wrong if I want to extend the WC_Widget_Product_Categories class?

Answer 1

When calling parent::__construct() from WC_Widget_Product_Departments the constructor of WC_Widget_Product_Categories immediately overwrites the class properties (especially the widget_id), see here at GitHub. So you have to extend WC_Widget to create a new widget and then you can copy anything what you need in your widget from WC_Widget_Product_Categories to WC_Widget_Product_Departments.