CODEWITHSUNDEEP
phpmagento
Gurpreet
Gurpreet

Reputation: 113

Can Observer break the Event in Magento?

I am new to Magento. I want to build an observer which on cancellation of an order will perform a query to my database and will decide whether the order is cancellable or not (This is decided on the basis of a certain state.). If it can't be cancelled, then it should break the cancel event and display a message that the order cannot be cancelled.

Which event I should choose, order_cancel_after or sales_order_item_cancel, and how can I break out of this event in between?

Thanks in advance. :)

Upvotes: 2

Views: 1579

Answers (1)

Fabian Schmengler
Fabian Schmengler

Reputation: 24551

There is no general answer to this, it depends on the context where the event is triggered and what happens there afterwards.

The events don't have an interface to "stop" them and they are not tied to the actual "event" (i.e. order cancellation) other than by name.

So you will have to look at the code of Mage_Sales_Model_Order_Item where sales_order_item_cancel gets triggered (order_cancel_after is obviously the wrong place to look because at that point the order is already cancelled):

/**
 * Cancel order item
 *
 * @return Mage_Sales_Model_Order_Item
 */
public function cancel()
{
    if ($this->getStatusId() !== self::STATUS_CANCELED) {
        Mage::dispatchEvent('sales_order_item_cancel', array('item'=>$this));
        $this->setQtyCanceled($this->getQtyToCancel());
        $this->setTaxCanceled($this->getTaxCanceled() + $this->getBaseTaxAmount() * $this->getQtyCanceled() / $this->getQtyOrdered());
        $this->setHiddenTaxCanceled($this->getHiddenTaxCanceled() + $this->getHiddenTaxAmount() * $this->getQtyCanceled() / $this->getQtyOrdered());
    }
    return $this;
}

You see that there is no additional check after the event was dispatched, but it would be possible to set the qty_to_cancel attributes to 0 to uneffect the cancelling.

Your observer method:

public function salesOrderItemCancel(Varien_Event_Observer $observer)
{
    $item = $observer->getEvent()->getItem();
    if (!$this->_isCancellable($item->getOrder())) {
        $item->setQtyToCancel(0);
        $this->_showErrorMessage();
    }
}

Note that you don't have to set tax_canceled or hidden_tax_canceled because they depend on qty_canceled and thus will stay 0.

Upvotes: 2

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