adding custom code to function addItem in Quote.php

Question

I looked for a way to add a custom order item.

Code -> Core -> Mage -> Sales -> Model -> Quote.php

See:

   public function addItem(Mage_Sales_Model_Quote_Item $item) {
       // Added: 
       $item->setTrainingLocation($_REQUEST[‘training_location’]);
       //Before: 
       $item->setQuote($this);
   }

Now for the above method I have to do changes in Magento core code. How can I do it via an observer or module.

This is what I have tried:

    <sales_quote_add_item>
        <observers>
            <addextraid>
                <type>singleton</type>
                <class>Mour_Customgroup_Model_Observer</class>
                <method>addextraparameter</method>
            </addextraid>
        </observers>
    </sales_quote_add_item>

And observer.php:

    public function addextraparameter($observer) {
        $item = $observer->getEvent()->getQuoteItem();
        $item->setCustomId(Mage::app()->getRequest()->getParam('custom_id'));
    }

Answer 1

You can use the event sales_quote_add_item. This is dispatched after $item->setQuote($this); but this should not be a problem unless you rewritten the setQuote method and use the value of training location in that one. I doubt you did this.

Here is a tutorial on how to create an observer.

Your method in the observer could look like this:

public function methodNameHere($observer) {
    $item = $observer->getEvent()->getQuoteItem();
    $item->setTrainingLocation(Mage::app()->getRequest()->getParam('training_location'));
}