add block in observer magento 1.9

Question

I need to show labels(BACK ON STOCK) on product when they back to stock, for this I have added a observer

    <global>
       <events>
       <catalog_product_save_commit_after> 
         <observers>
           <Name_StockLabel_Model_Observer> 
             <type>singleton</type> 
             <class>Name_StockLabel_Model_Observer</class> 
             <method>backInStock</method>  
            </Name_StockLabel_Model_Observer>
         </observers>
       </catalog_product_save_commit_after>
     </events>
   </global>

and in observer am adding trying to add block

 public function backInStock(Varien_Event_Observer $observer)
    {
        $product = $observer->getEvent()->getProduct();
        $stock = Mage::getModel('cataloginventory/stock_item')->loadByProduct($product->getId());
        $stockItem = $product->getStockItem();
        if ($stockItem->getCanBackInStock() && $stockItem->getQty() > $stockItem->getMinQty() && $stockItem->getIsInStock()){

            WANT TO ADD BLOCK HERE THAT WILL DISPLAY ON PRODUCT IN FRONTEND

        }
  }

Can anyone here advise me how can I add I block here

Answer 1

You can use an alternative way:

Create an attribute say back_on_stock with type Yes/No.

Change you event form catalog_product_save_commit_after to catalog_product_save_before.

Now in observer you can set this new attribute value in your if condition, like:

$product->setBackOnStock(1);
return $this;

Now in Your phtml, you can check this attribute value and show label

Hope above will help!

Answer 2

I don't think you need an observer for that.

Just add a conditon in your template (catalog/product/view.phtml), like this:

//$_product is Mage_Catalog_Model_Product object

<?php if ($this->displayProductStockStatus() && $_product->isAvailable()) :?>
    Stock is back
    <?php //echo $this->getLayout()->createBlock('cms/block')->setBlockId('your-block-id')->toHtml()?>
<?php endif;?>