Call custom function using events and observer

Question

I need to call our own custom function after save, delete, add products in Magento. I need to call in the separate file that is located in Magento root folder.

Answer 1

Magento has events for every controller action, both before and after executing. In your case you'll want to use catalog_product_delete_after and catalog_product_save_after.

I'm not really sure what you mean by add tho, is that for a new product? In that case you can observer ...save as well.

It would look something like this in your config.xml

<?xml version="1.0"?>
<config>
  <global>
    <models>
        <module]>
             <class>[Namespace]_[Module]_Model</class>
        </[module]>
    </models>
    <events>
      <catalog_product_save_after>
        <observers>
          <[namespace]_[module]_save_observer>
            <type>singleton</type>
            <class>[Namespace]_[Module]_Model_Observer</class>
            <method>save</method>
          </[namespace]_[module]_save_observer>
        </observers>
      </catalog_product_save_after>
      <catalog_product_save_delete>
        <observers>
          <[namespace]_[module]_delete_observer>
            <type>singleton</type>
            <class>[Namespace]_[Module]_Model_Observer</class>
            <method>delete</method>
          </[namespace]_[module]_delete_observer>
        </observers>
      </catalog_product_save_delete>     
    </events>
  </global>
</config>

For more info on observers please check this wikipage

Answer 2

Use the default events for these action catalog_product_save_after (and others), and create an observer that has some methods that act as wrappers for your custom functions. Something like:

<?php
require_once Mage::getBaseDir().'your_functions.php';
class Company_Module_Model_Observer{
    public function catalog_product_save_after($observer){
        $product = $observer->getEvent()->getProduct();
        yourFunction($product);//call function from your external file
    }
   //all other methods here
}

Even if this should work, I don't approve of this kind of code. You should keep the Magento standards and have your functions inside an observer.