Magento 1.7.0.2 Oberserver模块

Question

I am attempting to create an observer module based on this answer. The end result is to send an email when a specific product has been purchased and payment has been received. I hope to accomplish this by setting the observer to trigger when an order is completed. Thus far, I'm implemented the observer based on what I'd read in the above link and asked it to email me with the order info. So far it does absolutely nothing. Am I doing something wrong? the only modification I've made to what was provided is as follows:

/app/code/local/Electricjesus/Notifyowner/Model/Observer.php

<?php
class Electricjesus_Notifyowner_Model_Observer
{
    public function notifyOwnerEvent($observer)
    {

        // parameters you can get from the $observer parameter:
        // array(’payment’ ? $this, ‘invoice’ ? $invoice)

        $payment = $observer->getPayment();
        $invoice = $observer->getInvoice();

        // derivative data
        $order = $invoice->getOrder(); // Mage_Sales_Model_Order

        $email = array(
            'to' => 'me@mydomain.com',
            'subject' => 'Confirmed Purchase',
            'message' => 'Hello World. This is a test. $order = ' . $order,
            'headers' => 'From: My Store'
        ); 

        mail($email['to'], $email['subject'], $email['subject'], $email['headers']);

        /*
             - build data
             - build email structure
             - send email via any php mailer method you want
        */
        return $this;  // always return $this.
    }

}

I've also tried writing the relevant info to a file using file_put_contents('observer_log.txt', '$order = '.$order); to no effect. Any advice at all would be appreciated. I apologize for my noobishness.

EDIT: My config.xml [updated] file is as follows:

<?xml version="1.0"?>
<config>
    <modules>
        <Electricjesus_Notifyowner>
                <version>0.1.0</version>
        </Electricjesus_Notifyowner>
    </modules>
    <global>
        <models>
            <notifyowner>
                <class>Electricjesus_Notifyowner_Model</class>
            </notifyowner>
        </models>          
        <events>
                <sales_order_invoice_pay>
                    <observers>
                        <notifyOwnerEvent>
                                <class>notifyowner/observer</class>
                                <method>notifyOwnerEvent</method>
                        </notifyOwnerEvent>
                    </observers>
                </sales_order_invoice_pay>     
        </events>
     </global>
</config>

EDIT 2: I have since modified my config.xml It used to be

<events>
                    <sales_order_payment_pay>
                        <observers>

I changed the event to what you see above, though all the variables appear empty so I can't see if the order contains the product I care about before sending the email.

Answer 1

I finally got it figured out. For reasons I cannot begin to fathom, the documentation completely omits the information I wanted to know.

At any rate, in order to make an observer module that will send an email when a certain product is purchased and invoiced, you need the following:

/app/etc/modules/Electricjesus_Notifyowner.xml

<?xml version="1.0"?>
<config>
    <modules>
        <Electricjesus_Notifyowner>
            <active>true</active>
            <codePool>local</codePool>
        </Electricjesus_Notifyowner>
    </modules>
</config>

/app/code/local/Electricjesus/Notifyowner/etc/config.xml

<?xml version="1.0"?>
<config>
    <modules>
        <Electricjesus_Notifyowner>
                <version>0.1.0</version>
        </Electricjesus_Notifyowner>
    </modules>
    <global>
        <models>
            <notifyowner>
                <class>Electricjesus_Notifyowner_Model</class>
            </notifyowner>
        </models>          
        <events>
                <sales_order_invoice_pay>
                    <observers>
                        <notifyOwnerEvent>
                                <class>notifyowner/observer</class>
                                <method>notifyOwnerEvent</method>
                        </notifyOwnerEvent>
                    </observers>
                </sales_order_invoice_pay>     
        </events>
     </global>
</config>

and finally, /app/code/local/Electricjesus/Notifyowner/Model/Observer.php

<?php
class Electricjesus_Notifyowner_Model_Observer {
    public function notifyOwnerEvent($observer) {

        $invoice = $observer->getInvoice();

        // derivative data
        $order = $invoice->getOrder(); // Mage_Sales_Model_Order
        $items = $order->getAllItems();

        $i = 0;
        foreach($items as $item) {
            $str .= $item->getSku() . "/n";
            $skus[$i] = $item->getSku();
            $i++;
        }

        $shipAddr = $order->getBillingAddress();
        $billAddr = $order->getShippingAddress();
        $custName = $order->getCustomerName();

        $email = array(
            'to' => 'myname@maydomain.com',
            'subject' => 'Confirmed Purchase',
            'message' => '
                <html>
                    <body>
                        '. $custName .' has ordered and paid for the following products.
                        <table>
                            <th>
                                <td>
                                    Items Ordered
                                </td>
                                <td>
                                    Shipping Address
                                </td>
                                <td>
                                    Billing Address
                                </td>
                            </th>
                            <tr>
                                <td>
                                    '. $str .'
                                </td>
                                <td>
                                    '. $shipAddr .'
                                </td>
                                <td>
                                    '. $billAddr .'
                                </td>
                            </tr>
                        </table>
                    </body>
                </html>',
            'headers' => 'From: My Store'
        ); 

        $needle = 'mysku-01';

        if( in_array( $needle, $skus ) ) {
            mail($email['to'], $email['subject'], $email['message'], $email['headers']);
        }

        return $this;  // always return $this.
    }

}

Note that the product being detected is specified via $needle = 'mysku-01'; and the email itself is built via the $email[] array.