Question about customizing GA4

[ioweb-gr]

Hi,

I noticed a thing about GA4 purchase event

        /**
         *  This event signifies when one or more items is purchased by a user.
         *
         * @link https://developers.google.com/tag-platform/gtagjs/reference/events?hl=it#purchase
         */
        $orderIds = $this->getOrderIds();
        if (!empty($orderIds) && is_array($orderIds)) {
            $collection = Mage::getResourceModel('sales/order_collection')
                ->addFieldToFilter('entity_id', ['in' => $orderIds]);
            /** @var Mage_Sales_Model_Order $order */
            foreach ($collection as $order) {
                $orderData = [
                    'currency' => $order->getBaseCurrencyCode(),
                    'transaction_id' => $order->getIncrementId(),
                    'value' => $helper->formatPrice($order->getBaseGrandTotal()),
                    'coupon' => strtoupper((string)$order->getCouponCode()),
                    'shipping' => $helper->formatPrice($order->getBaseShippingAmount()),
                    'tax' => $helper->formatPrice($order->getBaseTaxAmount()),
                    'items' => []
                ];

                /** @var Mage_Sales_Model_Order_Item $item */
                foreach ($order->getAllItems() as $item) {
                    if ($item->getParentItem()) {
                        continue;
                    }
                    $_product = $item->getProduct();
                    $_item = [
                        'item_id' => $item->getSku(),
                        'item_name' => $item->getName(),
                        'quantity' => (int) $item->getQtyOrdered(),
                        'price' => $helper->formatPrice($item->getBasePrice()),
                        'discount' => $helper->formatPrice($item->getBaseDiscountAmount())
                    ];
                    if ($_product->getAttributeText('manufacturer')) {
                        $_item['item_brand'] = $_product->getAttributeText('manufacturer');
                    }
                    $itemCategory = $helper->getLastCategoryName($_product);
                    if ($itemCategory) {
                        $_item['item_category'] = $itemCategory;
                    }
                    array_push($orderData['items'], $_item);
                }
                $result[] = "gtag('event', 'purchase', " . json_encode($orderData, JSON_THROW_ON_ERROR) . ");";
            }
        }

        if ($this->helper('googleanalytics')->isDebugModeEnabled() && count($result) > 0) {
            $this->helper('googleanalytics')->log($result);
        }
        return implode("\n", $result);
    }

It seems this function doesn't take into account the possibility of custom fees that may affect the data.
For example cash on delivery fees, payment method fees additional shipping and handling fees.

In that case the only thing we can do is rewrite the whole block to customize the function to render the correct data.

Would it be possible to add an observer event here with a transport object that carries the $orderData before

$result[] = "gtag('event', 'purchase', " . json_encode($orderData, JSON_THROW_ON_ERROR) . ");";

So that we can add our own logic and modify the orderData?

[fballiano]

we should add an event, we just didn't do it yet because we needed this kind of feedback, let me know what would be the best solution for you and let's turn it into a PR :-)

[ioweb-gr]

I think that the data array for each event emitted for GA4 should be added in a transport object that can be modified as objects are passed by reference but arrays are passed by value then the final result should be the encoded value of the data array inside the transport object.

For example

Varien_Object $transport

Then $transport->setData('ga4_data', $eventDataArray)

Then the observer class can modify the ga4_data at will.

We could name the observer events based on the google event name for avoiding confusion.

E.g.

ga4_purchase_after

What do you think?

[fballiano]

I wanted to avoid throwing an event (openmage one) for every ga4 event, what if we create an array/object with all ga4 events and pass it to one single observer?

[ioweb-gr]

That's the same really not a problem. As long as everything is contained in the object is not a problem. An array won't work though it has to be an object to modify properly

[fballiano]

@ioweb-gr could you give #3448 a test?

[ioweb-gr]

I have one more consideration for this implementation aside from the data themselves.

The functions are restricted using the controller name.

In many installations we'll see onestep checkout extensions which will actually change the controller name.

For example

elseif ($moduleName == static::CHECKOUT_MODULE_NAME && $controllerName == static::CHECKOUT_CONTROLLER_NAME) {
            $productCollection = Mage::getSingleton('checkout/session')->getQuote()->getAllItems();
            if ($productCollection) {
                $eventData = [];
                $eventData['currency'] = Mage::app()->getStore()->getCurrentCurrencyCode();
                $eventData['value'] = 0.00;
                $eventData['items'] = [];
                foreach ($productCollection as $productInCart) {
                    if ($productInCart->getParentItem()) {
                        continue;
                    }
                    $_product = $productInCart->getProduct();
                    $_item = [
                        'item_id' => $_product->getSku(),
                        'item_name' => $_product->getName(),
                        'price' => $helper->formatPrice($_product->getFinalPrice()),
                        'quantity' => (int) $productInCart->getQty(),
                    ];
                    if ($_product->getAttributeText('manufacturer')) {
                        $_item['item_brand'] = $_product->getAttributeText('manufacturer');
                    }
                    $itemCategory = $helper->getLastCategoryName($_product);
                    if ($itemCategory) {
                        $_item['item_category'] = $itemCategory;
                    }
                    array_push($eventData['items'], $_item);
                    $eventData['value'] += $_product->getFinalPrice();
                }
                $eventData['value'] = $helper->formatPrice($eventData['value']);
                $result[] = ['begin_checkout', $eventData];
            }
        }

This one may not work. However we have no way to reuse it either. So again we have to resort to rewriting the whole block to actually achieve a modification.

Shouldn't those functions be moved to a helper instead so that they can be reused later on?

For example

elseif ($moduleName == static::CHECKOUT_MODULE_NAME && $controllerName == static::CHECKOUT_CONTROLLER_NAME) {
                $eventData = <GaHelper>->getBeginCheckoutEventData(); 
                $result[] = ['begin_checkout', $eventData];
            }
        }

I guess we can also override and extend the block and just modify the layout.xml to include our own custom block instead of the original one but still we have to modify a 300line function for just altering one area which is 20 lines of code.

I do think that the subactions should be their own protected functions for easier manipulation. What do you think?

[fballiano]

you can rewrite the block and just define those 2 constants:

<?php
 
class Customername_Analytics4_Block_GoogleAnalytics_Ga extends Mage_GoogleAnalytics_Block_Ga
{
    protected const CHECKOUT_MODULE_NAME = "firecheckout";
    protected const CHECKOUT_CONTROLLER_NAME = "index";
}

[ioweb-gr]

True :)