Change product price on all pages by using observer Magento - magento

Question

I am learning Magento and I have start learning events and observers. A percentage of amount is added to product by setting in admin product area.
It works fine but the discounted price shows only on product page. Can anybody suggest me how can I change the price through out Magento. I mean change price should go to cart, order etc.
Below is the code for observer
<?php
class Xyz_Catalog_Model_Price_Observer
{
public function __construct()
{
}
/**
* Applies the special price percentage discount
* #param Varien_Event_Observer $observer
* #return Xyz_Catalog_Model_Price_Observer
*/
public function apply_discount_percent($observer)
{
$event = $observer->getEvent();
$product = $event->getProduct();
// process percentage discounts only for simple products
if ($product->getSuperProduct() && $product->getSuperProduct()->isConfigurable()) {
} else {
$percentDiscount = $product->getPercentDiscount();
if (is_numeric($percentDiscount)) {
$today = floor(time()/86400)*86400;
$from = floor(strtotime($product->getSpecialFromDate())/86400)*86400;
$to = floor(strtotime($product->getSpecialToDate())/86400)*86400;
if ($product->getSpecialFromDate() && $today < $from) {
} elseif ($product->getSpecialToDate() && $today > $to) {
} else {
$price = $product->getPrice();
$finalPriceNow = $product->getData('final_price');
$specialPrice = $price - $price * $percentDiscount / 100;
// if special price is negative - negate the discount - this may be a mistake in data
if ($specialPrice < 0)
$specialPrice = $finalPriceNow;
if ($specialPrice < $finalPriceNow)
$product->setFinalPrice($specialPrice); // set the product final price
}
}
}
return $this;
}
}
config.xml
<?xml version="1.0"?>
<config>
<global>
<models>
<xyzcatalog>
<class>Xyz_Catalog_Model</class>
</xyzcatalog>
</models>
<events>
<catalog_product_get_final_price>
<observers>
<xyz_catalog_price_observer>
<type>singleton</type>
<class>Xyz_Catalog_Model_Price_Observer</class>
<method>apply_discount_percent</method>
</xyz_catalog_price_observer>
</observers>
</catalog_product_get_final_price>
</events>
</global>
</config>
Please advise how I can use the new discounted price throughout Magento. Thanks

Answer 1

Here is solution
config.xml
<?xml version="1.0"?>
<config>
<modules>
<Seta_DiscountPrice>
<version>0.1.0</version> <!-- Version number of your module -->
</Seta_DiscountPrice>
</modules>
<global>
<models>
<setadiscountprice>
<class>Seta_DiscountPrice_Model</class>
</setadiscountprice>
</models>
<events>
<catalog_product_get_final_price>
<observers>
<seta_discountprice_price_observer>
<type>singleton</type>
<class>Seta_DiscountPrice_Model_Price_Observer</class>
<method>apply_10</method>
</seta_discountprice_price_observer>
</observers>
</catalog_product_get_final_price>
<catalog_product_collection_load_after>
<observers>
<seta_discountprice_price_observer>
<type>singleton</type>
<class>Seta_DiscountPrice_Model_Price_Observer</class>
<method>apply_view</method>
</seta_discountprice_price_observer>
</observers>
</catalog_product_collection_load_after>
</events>
</global>
</config>
Observer.php
<?php
class Seta_DiscountPrice_Model_Price_Observer
{
public function __construct()
{
}
/**
* Applies the special price percentage discount
* #param Varien_Event_Observer $observer
* #return Seta_DiscountPrice_Model_Price_Observer
*/
public function apply_10($observer)
{
$event = $observer->getEvent();
$product = $event->getProduct();
// process percentage discounts only for simple products
if ($product->getSuperProduct() && $product->getSuperProduct()->isConfigurable()) {
} else {
$product->setFinalPrice(10);
}
return $this;
}
public function apply_view($observer)
{
$event = $observer->getEvent();
$myCustomPrice = 10;
$products = $observer->getCollection();
foreach( $products as $product )
{
$product->setPrice( $myCustomPrice );
$product->setFinalPrice( $myCustomPrice );
}
return $this;
}
}

Answer 2

Why not using 'catalog price rules' or 'special price' function of products? These are inbuilt functions to do this kind of stuff.
For add to cart price change, you need another event to observe. Crash course:
You have to build an observer that catches the add-to-cart event sales_quote_add_item and then you can do the php-stuff in the observer like you did on the product page to change the price for the product added to card with:
$observer->getEvent()->getQuoteItem()->setOriginalCustomPrice([your price])

Answer 3

Exactly for this task it's better to use Catalog Price Rules from Promotions menu.
But as I understand you are making this with learning purposes. So when you are not sure for an event you could just log the dispatched events. In app/Mage.php you have a method called dispatchEvent. Then you could just log every dispatched event:
public static function dispatchEvent($name, array $data = array())
{
if(strpos($name, 'product') || strpos($name, 'price')) { // optional
Mage::log($name, null, 'events.log', true);
}
Varien_Profiler::start('DISPATCH EVENT:'.$name);
$result = self::app()->dispatchEvent($name, $data);
Varien_Profiler::stop('DISPATCH EVENT:'.$name);
return $result;
}
Your log file will be created in var/log folder. Of course don't forget to revert Mage.php to it's original version when you're done. It's not a good idea to change core files.