Watching the Watchers

Sometimes when you’re tracking down a bit of tricky Magento functionality, you need to quickly suss out not only what events have fired, but which observers methods are actually listening for the events that fired on a particular request.

There’s no elegant way to doing this with Magento, but if you’re not above a little temporary logging code in core files (moved to the local code pool, of course), then a few extra lines at the start of _callObserverMethod is what you want.

#File: app/code/core/Mage/Core/Model/App.php

protected function _callObserverMethod($object, $method, $observer)
{
    $log = 'Trying to call ' . $method . ' on ' . get_class($object)
    . ' for ' . $observer->getEvent()->getName();
    file_put_contents('/tmp/test.log',"$log n",FILE_APPEND);
    Mage::Log($log);            

    if (method_exists($object, $method)) {            
        $object->$method($observer);
    } elseif (Mage::getIsDeveloperMode()) {
        Mage::throwException('Method "'.$method.'" is not defined in "'.get_class($object).'"');
    }
    return $this;
}