Example code for http://magento.stackexchange.com/questions/10566/sort-catalogsearch-by-2-attributes/10589. Please check the README.md

README.md

Example code for http://magento.stackexchange.com/questions/10566/sort-catalogsearch-by-2-attributes/10589.

Files:

• app/code/community/Emzee/Sorter/etc/config.xml
• app/code/community/Emzee/Sorter/Model/Observer.php
• app/etc/modules/Emzee_Sorter.xml

config.xml

<?xml version="1.0"?>
<config>
    <modules>
        <Emzee_Sorter>
            <version>1.0.0</version>
        </Emzee_Sorter>
    </modules>
    <global>
        <models>
            <emzee_sorter>
                <class>Emzee_Sorter_Model</class>
            </emzee_sorter>
        </models>
        <events>
            <catalog_block_product_list_collection>
                <observers>
                    <emzee_sorter>
                        <class>emzee_sorter/observer</class>
                        <method>catalogBlockProductListCollection</method>
                    </emzee_sorter>
                </observers>
            </catalog_block_product_list_collection>
        </events>
    </global>
</config>

Emzee_Sorter.xml

<?xml version="1.0"?>
<config>
    <modules>
        <Emzee_Sorter>
            <active>true</active>
            <codePool>community</codePool>
            <depends></depends>
        </Emzee_Sorter>
    </modules>
</config>

Observer.php

<?php

class Emzee_Sorter_Model_Observer
{
    /**
     * @param Varien_Event_Observer $observer
     * @return Emzee_Sorter_Model_Observer
     */
    public function catalogBlockProductListCollection(Varien_Event_Observer $observer)
    {
        $request = Mage::app()->getFrontController()->getRequest();
        $action = $request->getModuleName() . '_' . $request->getControllerName() . '_' . $request->getActionName();
        if ($action === 'catalogsearch_result_index' || $action === 'catalogsearch_advanced_result') {
            $collection = $observer->getEvent()->getCollection();
            $collection->addOrder('sort_2', Varien_Data_Collection::SORT_ORDER_DESC);
        }
        return $this;
    }
}