send email for out of stock

Question

How to send sms when an item quantity is out of stock in magento ? i have used :

<catalog_product_save_before>
    <observers>
        <Metro_Notify>
            <type>singleton</type>
            <class>notify/Productobserver</class>
            <method>productSaveBefore</method>
        </Metro_Notify>
    </observers>
</catalog_product_save_before>

in my observer

private function lowStockReportSendEmail($product,$toEmailAddress)
{
    $stockItem = $observer->getEvent();
    Mage::log($stockItem,null,'stockitem.null');

    if($stockItem->getQty() < $stockItem->getNotifyStockQty())
    {
       //stock is lower than the notify amount, send email
       $product = $observer->getProduct();  
       $productName =  $product->getName();
       $productId =  $product->getId();
       $supplierId = $product->getSeller_id();
       $supplierData = $this->_getSupplierData($supplierId);

       // $product = Mage::getModel('catalog/product')->load($stockItem->getProductId());

        $body = "{$productName} :: {$product->getSku()} just Ran out of stock:\n\n";
        $body .= "Current Qty: {$stockItem->getQty()}\n";
        $body .= "Low Stock Date: {$stockItem->getLowStockDate()}\n";

        $vars['PRODUCTID'] = $productData->getId();
        $vars['PRODUCTNAME'] = $productData->getName();
        $vars['SUPPLIERNAME'] = $supplierData->getFirstname();          
        $vars['SUPPLIERNO'] = $supplierData->getSupplier_no();
        $vars['QTY'] = $stockItem->getQty();
        $vars['PREVIOUSQTY'] = $stockItem->getQty() - $stockItem->getOrigData('qty');

        $categoryManagerTemplateId = 'categorymanager_template_lowstock_report';
        $adminTemplateId = 'admin_template_lowstock_report';
        $fromEmailId = $supplierData->getEmail();
        $sender = array('name' => $fromEmailId,'email' => $fromEmailId);    

        if(!empty($toEmailAddress))
        {
            $categoryManagerEmail = $toEmailAddress;                
            $adminEmail = $toEmailAddress;  
        }   
        else
        {
            $categoryManagerEmail = $supplierData->getSupplier_cat_manager_email();
            $adminEmail = $this->_getAdminEmailAddress();                           
            $this->log('categoryManagerEmail',$categoryManagerEmail);
            $this->log('adminEmail',$adminEmail);
        }

        /* $storeId = Mage::app()->getStore()->getId();
        $templateId = 'supplier_product_stock_update';
        $fromEmailId = $supplierData->getEmail();               
        $sender = array('name' => $fromEmailId,'email' => $fromEmailId);
        $toEmail = $supplierData->getSupplier_cat_manager_email();
        $name = $supplierData->getFirstname();
        $mailSubject = "Supplier Low Stock Notification"; */
        $name = $supplierData->getFirstname();

        $mailCategorySubject = "Out of Stock".$productName."(".$productId.")";
        $mailAdminSubject="Out of Stock".$supplierName;

        $this->_sendNotifyEmail($categoryManagerTemplateId, $sender, $categoryManagerEmail, $name, $mailCategorySubject,$vars, $storeId);
        $this->_sendNotifyEmail($adminTemplateId, $sender, $adminEmail, $name, $mailAdminSubject,$vars, $storeId);
        $this->log('LowStockReportEmail',$vars);
    }
}

Answer 1

catalog_product_save_before is only triggered when the product is saved from the backend, not when stock decreases after ordering. You need to observe sales_order_place_after as well (unfortunately you cannot use any event related to the stock item model, because Magento uses an optimized SQL query to decrease stock for all ordered items at once, bypassing the model).

An alternative (that's how I solved it), is to rewrite Mage_CatalogInventory_Model_Stock and add an additional event:

<?php
/**
 * Add events to observe stock qty change
 * 
 * @author Fabian Schmengler
 *
 */
class SGH_ShippingExpress_Model_CatalogInventory_Stock
    extends Mage_CatalogInventory_Model_Stock
{
    const EVENT_CORRECT_STOCK_ITEMS_QTY_BEFORE = 'cataloginventory_stock_item_correct_qty_before';
    const EVENT_CORRECT_STOCK_ITEMS_QTY_AFTER = 'cataloginventory_stock_item_correct_qty_after';

    /**
     * (non-PHPdoc)
     * @see Mage_CatalogInventory_Model_Stock::registerProductsSale()
     */
    public function registerProductsSale($items)
    {
        Mage::dispatchEvent(self::EVENT_CORRECT_STOCK_ITEMS_QTY_BEFORE, array(
            'stock'     => $this,
            'items_obj' => (object)array('items' => &$items),
            'operator'  => '+'
        ));
        $result = parent::registerProductsSale($items);
        Mage::dispatchEvent(self::EVENT_CORRECT_STOCK_ITEMS_QTY_AFTER, array(
            'stock'          => $this,
            'items'          => $items,
            'fullsave_items' => $result,
            'operator'       => '+'
        ));
        return $result;
    }
    /**
     * (non-PHPdoc)
     * @see Mage_CatalogInventory_Model_Stock::revertProductsSale()
     */
    public function revertProductsSale($items)
    {
        Mage::dispatchEvent(self::EVENT_CORRECT_STOCK_ITEMS_QTY_BEFORE, array(
            'stock'     => $this,
            'items_obj' => (object)array('items' => &$items),
            'operator'  => '-'
        ));
        $result = parent::revertProductsSale($items);
        Mage::dispatchEvent(self::EVENT_CORRECT_STOCK_ITEMS_QTY_BEFORE, array(
            'stock'          => $this,
            'items'          => $items,
            'fullsave_items' => $result,
            'operator'       => '-'
        ));
        return $result;
    }
}

Then the observer for cataloginventory_stock_item_correct_qty_after can look like this:

    /**
     * @var $items array array($productId => array('qty'=>$qty, 'item'=>$stockItem))
     */
    $items = $observer->getItems();
    foreach ($items as $productId => $item) {
        $stockItem = $item['item'];
        $product = $stockItem->getProduct();

        // Do anything you need with $stockItem and $product here

    }

I recommend not to check if they are out of stock at this point, but to add the products to a queue that is processed by a cronjob, to minimize additional load time for the user.

Answer 2

You are getting your stockItem from the $observer however you've changed the parameters of your function, therefor $stockItem = $observer->getEvent(); can't get anything because $observer does not exist...

From your OP we can see you are using the $observer inside the lowStockReportSendEmail function, however the observer is not present here!

Assuming you have the observer, and in that function you create $product and $toEmailAddress before calling lowStockReportSendEmail you should have :

private function lowStockReportSendEmail($observer, $product, $toEmailAddress)
{
    $stockItem = $observer->getEvent();
[...]

And in the code that calls the funtion, obviously $this->lowStockReportSendEmail($observer, $product, $toEmailAddress);