Answers for "woocommerce get category id from product on order"

woocommerce get product category name by id

$id = 42;
if( $term = get_term_by( 'id', $id, 'product_cat' ) ){
    echo $term->name;
}

woocommerce order item get product id

foreach ( $items as $item ) {
    $product_name = $item->get_name();
    $product_id = $item->get_product_id();
    $product_variation_id = $item->get_variation_id();
}