Magento 2.1 Module – Record Product Changes and Changer

catalogevent-observermagento-2.1module

In Magento2.1, I want to make a module to record the product change and changer in database. I think I can use events and observers to achieve it. The catalog_product_save_after event maybe is a good beginning.

But, when I use the event, how can I know what is the specific attribute the user changed? For example, the price change. How can I know the user changed the price, instead of changing anything else?

Maybe Magento2 has a better event for the specific attribute change? Or a good way to distinguish the price change or anything else? Any suggestion is welcome, thanks 🙂

Best Answer

Event

Use the catalog_product_save_after event in the Vendor/Model/etc/adminhtml/events.xml

<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:Event/etc/events.xsd">
    <event name="catalog_product_save_after">
        <observer name="the_observer_name" instance="Vendor\Module\Observer\ProductSaveAfter" />
    </event>
</config>

Observer

In the Observer, use the $observer->getProduct()->getOrigData('...') is the point to get specific attribute change.

<?php
namespace Vendor\Module\Observer;

use Magento\Framework\Event\Observer;
use Magento\Framework\Event\ObserverInterface;

class ProductSaveAfter implements ObserverInterface
{
    public function execute(Observer $observer)
    {
        $product = $observer->getProduct();
        // you could add more product attributes to the $compareArray
        $compareArray = ['sku','price','special_price','cost','weight','special_from_date','special_to_date','status','visibility','is_salable'];
        $event = "";
        foreach ($compareArray as $value) {
            $old = $product->getOrigData($value);
            $new = $product->getData($value);
            if ($old !== $new) {
                $event .= " Change $value $old=>$new.";
            }
        }
        // other codes and write the $event to DB
    }
}

In the Observer, use the Magento\Backend\Model\Auth\Session to get the changer.

<?php
namespace Vendor\Module\Observer;

use Magento\Backend\Model\Auth\Session;
use Magento\Framework\Event\Observer;
use Magento\Framework\Event\ObserverInterface;

class ProductSaveAfter implements ObserverInterface
{
    protected $authSession;

    public function __construct(
        Session $authSession
    )
    {
        $this->authSession = $authSession;
    }

    public function execute(Observer $observer)
    {
        $user = $this->authSession->getUser();
        $userId = $user->getId();
        $userName = $user->getUsername();
        // other codes
    }
}

Merge above two Observer parts, now you get the product changes and changer, write them to the DB, then the function is finished.

Related Solutions

Magento – add product to cart and change price and weight

Try adding an observer for event event 'sales_quote_add_item':

<events>
    <sales_quote_add_item>
        <observers>
            <priceupdate_observer>
                <type>singleton</type>
                <class>mymodule/observer</class>
                <method>updatePrice</method>
            </priceupdate_observer>
        </observers>
    </sales_quote_add_item>
</events>

In your observer :

public function updatePrice($observer) {
    $event = $observer->getEvent();
    $quote_item = $event->getQuoteItem();

    $product = $quote_item->getProduct(); //You may need to load the product module or add the attribute to flat table
    $new_price = <insert logic>
    $quote_item->setOriginalCustomPrice($new_price);
    $quote_item->setWeight($newWeight);
    $quote_item->save();
}

See https://stackoverflow.com/questions/9721583/changing-the-price-in-quote-while-adding-product-to-cart-magento

Magento2 Event Observer – Get Product Custom Attribute

If you are listening on checkout_cart_add_product_complete you have the following items on the $observer

 ['product' => $product, 'request' => $this->getRequest(), 'response' => $this->getResponse()]

Your code should look smth like this

$product = $observer->getProduct(); // or $observer->getData('product');
$customAttribute = $product->getCustomAttribute('custom_attribute_code');
// to avoid errors double check that this product 
// has the custom attribute associated to it
$value = $customAttribute !== null ? $customAttribute->getValue() : null;

It's also a good practice to use the debugger to see what is what and what properties and values are available on a given object.

Hope this helps. Cheers.

EDIT as result of the comment

You do not have the product loaded at that point. You only have the controller instance and the request as it can be seen \Magento\Framework\App\Action\Action::dispatch(). You must have smth on the request like a product_id or product_sku.

In a development environment if you don't have xdebug(you should really take care of that, it pays off) the fastest way to debug stuff is var_dump($object->getData()).

On this specific event what you can do is inject the product repository in the constructor, get the product id from the request and load the product.

smth like

$product = $this->productRepository->getById($observer->getRequest()->getProductId())

Once you have the product above should apply. You can add some extra checks like, is there a request on the observer data? is there a product id on the request and so on.