Question

I have written a simple Magento plugin that simply lists all sub categories that are enabled from a given parent id.

The user simply selects a parent category id from the admin using the plugin tab i have created.

To speed things up i have added block caching to the plugin using the following code

 $this->addData(array(
            'cache_lifetime' => 86400,
            'cache_tags' => array(Mage_Catalog_Model_Category::CACHE_TAG)
        ));

This works well so far, as if a sub category is enabled / disabled the cache invalidates and is replaced. However if i change the parent category id in the admin changes are not seen until the whole block cache is refreshed using system->cache managment.

What i would like to do is have a method where by when a user clicks save in the admin the cache is flushed for just this one block rather than refreshing everything.

How would i go about this ? i am thinking some sort of event observer on the save event in adminhtml? however i wouldn’t know how to do this.

I am interested on what thoughs / suggestions other people may have.

Many thanks

Ian Cassidy

Answer 1

You can use an Event Observer to clean cache. You can follow this tutorial to setup your observers, and then observe the catalog_category_save_after event.

To clear cache, use Mage::app()->getCacheInstance()->cleanType(Mage_Catalog_Model_Category::CACHE_TAG); in your Observer Model.

PS: maybe you have to setup your <events> into <admin> or <adminhtml> instead of <globals>.