Code-Snippets-Functions/Execute a function on a child site/WooCommerce/add-regular-price-add-extra-additional-flat-price.txt

add_action( 'woocommerce_admin_process_product_object', 'woocommerce_admin_process_product_object_callback' );
add_action( 'woocommerce_admin_process_variation_object', 'woocommerce_admin_process_product_object_callback' );
function woocommerce_admin_process_product_object_callback( $product ) {
    if ( $product->get_meta('_flat_amount_added') !== 'yes' && isset($_POST['_regular_price']) ) {
        $flat_amount = 5; // Define the flat amount to be added to the regular price

        $regular_price = (float) $product->get_regular_price('edit');
        $product->set_regular_price($regular_price + $flat_amount);
        $product->add_meta_data('_flat_amount_added', 'yes', true);
    }
}