Woocommerce DYMO Print - Print custom field of variation products

functions.php

//Tested on ycb.vn
function filter_wc_dymo_product($output,$object,$product,$variation,$labelID) {
 
    if($labelID=='product') {
		if(!empty($variation)) {
			$barcode = get_post_meta( $variation->get_id(), '_barcode', true );
		} else {
			$barcode = get_post_meta( $product->get_id(), '_barcode', true );
		}		
		$output[0]['BARCODE'] = $barcode;
	}
    return $output;
}
 
// add the filter
add_filter('wc_dymo_product','filter_wc_dymo_product',20,5);