WooCommerce - show "Manage stock levels" option for a custom product type

Question

I've added a custom product type to my woocommerce site called "Gift Card", and enabled the "Inventory" product data tab using the following code:

// Register the product type
function register_product_type () {

    class WC_Product_Gift_Card extends WC_Product {

        public function __construct( $product ) {
            $this->product_type = 'gift_card';
            parent::__construct( $product );
            // add additional functions here
        }

    }
}
add_action( 'init', 'register_product_type' );

// Add the product type to the dropdown select
function add_product_type ( $type ) {
    $type[ 'gift_card' ] = __( 'Gift Card' );
    return $type;
}
add_filter( 'product_type_selector', 'add_product_type' );

// Show the "Inventory" tab and hide the "Shipping" tab
function product_data_tabs( $tabs ) {
    global $post, $product_object;

    if ( $product_object && $product_object->is_type( 'gift_card' ) ) {
        $tabs['inventory']['class'][] = 'show_if_gift_card';
        unset( $tabs['shipping'] );
    }
    return $tabs;
}
add_filter( 'woocommerce_product_data_tabs', 'product_data_tabs', 10, 1 );

However, on the Inventory tab, the "Manage stock levels (quantity)" option isn't shown. I've tried enabling it with the following code but it throws an error:

function show_manage_stock_options( $panels ) {
    global $product_object;

    if ( $product_object && $product_object->is_type( 'gift_card' ) ) {
        $inventory_panel = $panels['inventory'];
        $inventory_panel['fields']['manage_stock']['class'][] = 'show_if_gift_card';
        $inventory_panel['fields']['stock_quantity']['class'][] = 'show_if_gift_card';
        $panels['inventory'] = $inventory_panel;
    }

    return $panels;
}
add_filter( 'woocommerce_product_data_panels', 'show_manage_stock_options', 10, 2 );

Where am I going wrong?

Answer 1

just handle it with javascript

function woo_add_gift_card() {
    if ( 'product' != get_post_type() ) :
        return;
    endif;
    ?>
    <script type='text/javascript'>
        jQuery(document).ready(function () {
            //for Price tab
            jQuery('.product_data_tabs .general_tab').addClass('show_if_gift_card').show();
            jQuery('#general_product_data .pricing').addClass('show_if_gift_card').show();
            //for Inventory tab
            jQuery('.inventory_options').addClass('show_if_gift_card').show();
            jQuery('#inventory_product_data ._manage_stock_field').addClass('show_if_gift_card').show();
            jQuery('#inventory_product_data ._sold_individually_field').parent().addClass('show_if_gift_card').show();
            jQuery('#inventory_product_data ._sold_individually_field').addClass('show_if_gift_card').show();
        });
    </script>
    <?php

}
add_action( 'admin_footer', 'woo_add_gift_card' );