Apply an extra filter in view

Question

I am trying to add additional filters to a collection after the collection seems to of been generated. In catalogue product list.phtml there is the following line of code:

$_productCollection = $this->getLoadedProductCollection();

When I var_dump this it does report back as a collection (Mage_Catalog_Model_Resource_Product_Collection). However if I try to add:

$_productCollection->addAttributeToFilter('attr_handle', array('eq' => 155));

directly after the first line, the resulting collection is still exactly the same. How can I modify what is in $_productCollection in list.phtml?

Any help is appreciated

---- UPDATE ----

I notice that in the List.php block the collection is loaded in the _beforeToHtml method:

$this->_getProductCollection()->load();

I am assuming therefore I have to "unload" (?) it and then apply my filters in the view and then re-load it (?)

Answer 1

You can call $collection->clear(), apply your filters, and then reload the collection. However IIRC the collection will be in a different state than the layer model expects.

This a combination of both Mage_Catalog_Model_Resource_Product_Collection::clear() and Varien_Data_Collection::clear().

Answer 2

You can filter product collection before loading. See following, your config.xml

<frontend>   
       <events>
            <catalog_product_collection_load_before>
                <observers>
                    <ssd_ajaxify>
                        <class>SSD_Ajaxify_Model_Observer</class>
                        <method>catalogProductCollectionLoadBefore</method>
                    </ssd_ajaxify>
                </observers>
            </catalog_product_collection_load_before>
        </events>
</frontend>

And Observer.php:

class SSD_Ajaxify_Model_Observer
{    
public function catalogProductCollectionLoadBefore($observer)
        {
            $request = Mage::app()->getRequest();
            $path    = implode('_', array(
                $request->getModuleName(),
                $request->getControllerName(),
                $request->getActionName(),
            ));
            if ($path == 'catalog_category_view') {
                $collection = $observer->getEvent()->getCollection();
                $collection->addAttributeToFilter('price', array('gt'=> 50));
            }
        }
}

By the way this affects to your toolbar and layered navigation, and also product list in category view page.

Answer 3

By using rewrite Magento Product List Block, we can add an extra filter in product collection.

Please use below link for reference:-
[http://shariqnasir.blogspot.in/2011/06/override-core-modules.html][1]
[http://pratikkhamar.wordpress.com/2012/04/13/magentooverride-block/][2]

Hope this will help you.