Magento – Magento invoices logic, payment methods

Karl,goto app/code/core/Mage/Paypal/Model/Ipn.php
copy to

app/code/local/Mage/Paypal/Model/Ipn.php

here magento create invoice on paypal order

find the code:

app/code/core/Mage/Paypal/Model/Ipn.php goto function

here create invoice by below code:

if ($invoice = $payment->getCreatedInvoice()) {
            $message = Mage::helper('paypal')->__('Notified customer about invoice #%s.', $invoice->getIncrementId());
            $comment = $order->sendNewOrderEmail()->addStatusHistoryComment($message)
                ->setIsCustomerNotified(true)
                ->save();
        }

just change it to

$order->sendNewOrderEmail()
                ->setIsCustomerNotified(true)
                ->save();

here function $payment->getCreatedInvoice() create invoice of an order

or used the extension:

http://www.magentocommerce.com/magento-connect/disable-automatic-generation-of-invoice.html

You should create an simple extension and have some observer to listen sales then do whatever you would like to.

In your etc/config.xml

<global>
  ......
  <events>
         <sales_order_place_after>
            <observers>
                <send_invoice>
                        <type>singleton</type>
                        <class>NameSpace_ModuleName_Model_Observer</class>
                        <method>sendInvoice</method>
                    </send_invoice>
            </observers>
        </sales_order_place_after>
  </events>
  ......
</global>

Now NameSpace_ModuleName_Model_Observer.php

class NameSpace_ModuleName_Model_Observer
{
   public function sendInvoice($observer) {
    $order = $observer->getEvent()->getOrder();

    //check order payment
    if($this->_getPaymentMethod($order) == 'payment_method'){
       if($order->canInvoice())
       {
           $invoice = Mage::getModel('sales/service_order', $order)->prepareInvoice();
           $invoice->setRequestedCaptureCase(Mage_Sales_Model_Order_Invoice::CAPTURE_ONLINE);
           $invoice->register();
           $transactionSave = Mage::getModel('core/resource_transaction')
           ->addObject($invoice)
           ->addObject($invoice->getOrder());
           $transactionSave->save();

           //send invoice
           $invoice->sendEmail();
       }
    }

    //get payment method code
    protected function _getPaymentMethod($order)
    {
       return $order->getPayment()->getMethodInstance()->getCode();
    }
}

you will have to find out your payment method code and replace with payment_method.

Hope this helps.