Changes in item meta_data on payment_completed - wordpress

Question

I want change add/change a meta_data in order item after complete a payment
is somethink like add a custom field with random number.
How I can make that ?
I dont found how
public function process_payment( $order_id ) {
global $woocommerce;
$order = new WC_Order( $order_id );
// Mark as on-hold (we're awaiting the cheque)
if ( 'yes' == $this->debug ) {
$this->log->add( 'Compra', "IPN Response Loggin test" );
}
$order->get_items();
if ( sizeof( $order->get_items() ) > 0 ) {
foreach ( $order->get_items() as $item ) {
if ( ! $item['qty'] ) {
continue;
}
// Any information about function to edit meta data in item ?
}
}
$order->payment_complete();
// Reduce stock levels
$order->reduce_order_stock();
// Remove cart
$woocommerce->cart->empty_cart();
// Return thankyou redirect
return array(
'result' => 'success',
'redirect' => $this->get_return_url( $order )
);
}

Answer 1

Use wc_update_order_item_meta for this purpose.
Try this
if ( sizeof( $order->get_items() ) > 0 ) {
foreach ( $order->get_items() as $id => $item ) {
if ( ! $item['qty'] ) {
continue;
}
// Any information about function to edit meta data in item ?
wc_update_order_item_meta( $id, 'your meta key', 'new value' );
}
}

Answer 2

If you look at the payment_complete() method in the Order abstract class you will see the woocommerce_payment_complete action hook. If you want to run something when the payment is completed, then you would attach your function to this hook. Without really understanding what you are doing, the following will simply add a random number (not necessarily unique) to each item in the order.
add_action( 'woocommerce_payment_complete', 'so_27852832_item_data' );
function so_27852832_item_data( $order_id ){
$order = new WC_Order( $order_id );
if ( sizeof( $order->get_items() ) > 0 ) {
foreach ( $order->get_items() as $id => $item ) {
wc_update_order_item_meta( $id, '_random_number', rand() );
}
}
}