Adding a 'featured' filter to WooCommerce products screen

gistfile1.txt

// Add a custom filter to the query
add_action('pre_get_posts', 'featured_products_admin_filter_query');
function featured_products_admin_filter_query($query) {
    global $pagenow;
    if (is_admin() && $pagenow == 'edit.php' && isset($_GET['post_type']) && $_GET['post_type'] == 'product' && isset($_GET['is_featured']) && $_GET['is_featured'] == '1') {
        $query->set('tax_query', array(
            array(
                'taxonomy' => 'product_visibility',
                'field'    => 'name',
                'terms'    => 'featured',
            )
        ));
    }
}

// Add the custom filter to the admin page
add_action('restrict_manage_posts', 'featured_products_admin_filter');
function featured_products_admin_filter() {
    global $typenow;
    if ($typenow == 'product') {
        $filter_id = 'is_featured';
        $current = isset($_GET[$filter_id]) ? $_GET[$filter_id] : '';
        echo '<select name="' . $filter_id . '">';
        echo '<option value="">' . __('All products', 'woocommerce') . '</option>';
        echo '<option value="1" ' . selected($current, '1', false) . '>' . __('Featured', 'woocommerce') . '</option>';
        echo '</select>';
    }
}