Creating custom event observer for after sale

Question

I'm attempting to create a custom observer that will trigger after a successful purchase has been made. I assume that sales_order_save_after is the correct event to use.

What the Observer will do is check to make sure the order is coming from the correct store, and then add some data into a new table. I thought I had done it correctly, but couldn't get it to work. After a bit of changing some things, I eventually glitched my test account I was making purchases on. It now receives this error whenever trying to checkout: Payment has already been made for this InvoiceID (#10412: Duplicate invoice)

Regardless, this is what I have:

Observer.php

<?php

class Namespace_Module_Model_Observer {

    public function saveData(Varien_Event_Observer $observer) {

    $order = $observer->getEvent()->getOrder();
    $storeId = $order->getStoreId();


    $incrementId = $order->getIncrementId();
    $entity_id = $order->getEntityId();

    if($storeId == 3){
       // saving data via query
    }

config.xml

<config>

<global>
    <models>
        <namespace>
            <class>Namespace_Module_Model</class>
        </namespace>
    </models>
    <events>
        <sales_order_place_after>
            <observers>
                <namespace_module_savedata>
                    <class>Namespace_Module_Model_Observer</class>
                    <method>saveData</method>
                    <type>singleton</type>
                </namespace_module_savedata>
            </observers>
        </sales_order_place_after>
    </events>
</global>
</config>

Is everything here look correct? I just realized I had Namespace_Module_Model_Observer/observer as the class before copying the code here. However, prior to that, I was still getting nothing for the most part. No errors/exceptions. I haven't tried adding an actual log dispatch to the observer yet though. Would that just be: Mage::log($observer->getEvent()->getName(),null,'event.log');?

Answer 1

I had a problem with the sales_order_save_after event as it triggers twice after orders are placed. Maybe that's why your saveData() function tries to save data twice. Try sales_order_place_after instead.