Invoicing a partial order; totals aren't updated - php

Question

In our order proces it is possible to send an invoice for a partial order. So when a couple of order lines are being shipped, an invoice have to be send also.
To make this possible I use this code:
$invoice = Mage::getModel('sales/service_order', $order)->prepareInvoice($items);
if (!$invoice->getTotalQty()) {
Mage::throwException(Mage::helper('core')->__('Cannot create an invoice without products.'));
}
$invoice->setRequestedCaptureCase(Mage_Sales_Model_Order_Invoice::CAPTURE_ONLINE);
$invoice->register();
$transactionSave = Mage::getModel('core/resource_transaction')
->addObject($invoice)
->addObject($invoice->getOrder());
$transactionSave->save();
$invoice->sendEmail();
$invoice->setEmailSent(true);
$invoice->save();
Where the $items variable is an array containing the order ids and the amount of products to be invoiced.
The created invoice shows the correct products to be invoiced, but somehow the totals aren't updated. The totals still are the totals of the complete order, instead of the partial invoice.
I probably have to update or recalculate the totals but can't find the right code to force the update.
Anyone around who can put me in the right direction?

Answer 1

Well, it seems I have found the problem. The functionality as described above works manually executing it in the administrator interface. The code as enclosed above I only got to work by changing a core file of Magento.
If you change line 103 of Mage_Sales_Model_Service_Order from continue; to $qty = 0; the functionality works.
In short, this is what happens. With continue the second row item isn't added to the invoice which the invoice makes thinks the curren item is the last item of the whole order and therefore needs to invoice the complete outstanding amount. In my case the invoice I did want to invoice and the row I didn't want to invoice.
I've submitted it as issue on the Magento issue list.

Answer 2

Today I faced with exactly this problem, but I found a more elegant way to solve it without editing the core. The solution is to pass the products that we don't want to invoice, with 0 quantity.
In this way, the code you changed in core will act exactly like in your solution :)
As an example if I have 2 products in my order:
array(
1234 => 1,
1235 => 2
)
passing this array:
$qtys = array(
1234 => 1,
1235 => 0
)
will force this code:
// Mage_Sales_Model_Service_Order: lines 97-103
if (isset($qtys[$orderItem->getId()])) { // here's the magic
$qty = (float) $qtys[$orderItem->getId()];
} elseif (!count($qtys)) {
$qty = $orderItem->getQtyToInvoice();
} else {
continue; // the line to edit according to previous solution
}
to act exactly like in your solution, so you don't have to edit core code.
Hope it helps :)

Answer 3

OK - took me a bit, but now I see how to correctly create the array.
foreach ($items as $itemId => $item) {
$itemQtyToShip = $item->getQtyToShip()*1;
if ($itemQtyToShip>0) {
$itemQtyOnHand = $stockItem->getQty()*1;
if ($itemQtyOnHand>0) {
//use the order item id as key
//set the amount to invoice for as the value
$toShip[$item->getId()] = $itemQtyToShip;
} else {
//if not shipping the item set the qty to 0
$toShip[$item->getId()] = 0;
}
}
$invoice = Mage::getModel('sales/service_order', $order)->prepareInvoice($toShip);
This creates a proper invoice.