Bug: remove-from-cart tracking broken

Hi Pixel Manager team,

First of all, thank you for a great plugin! It has saved us an enormous amount of time setting up conversion tracking. We have, however, stumbled upon a bug we want to report. I believe this bug is not specific to my environment but is a bug in your plugin.

Environment: Pixel Manager for WooCommerce (free, v1.67.0), WooCommerce (10.9.4), Flatsome theme with child theme.

The bug is, in short, that remove-from-cart tracking is broken due to a mismatch in how cart_item_keys are handled, which produces the “Wasn’t able to retrieve a productId” error message. Let me describe this in detail.

When a customer removes a product from the cart (mini-cart, cart and checkout), the Js-console in Chrome show the following error:

Pixel Manager: error: Error: Wasn't able to retrieve a productId
    at e.removeProductFromCart (functions.js:171)
    at HTMLAnchorElement.<anonymous> (event_listeners.js:159)

This results in the pmw:remove-from-cart event nevr being sent.

Steps to reproduce: Add any product to the cart, then load any page with the product in the cart, finally click a remove-from-cart button/link.

Root cause: I had a long debug session where I managed to trace where things go wrong. A data-format mismatch inside the plugin between the backend cart sync and the remove-link resolver:

1. ajax_pmw_get_cart_items() returns cart item keys as cart_item_keys[key] = { id, is_variation, parent_id }

// class-pixel-manager.php
$data['cart'][$product->get_id()]['variant'] = (string) implode( ' | ', $variant_text_array );
$data['cart_item_keys'][$cart_item]['parent_id'] = (string) $product->get_parent_id();
$data['cart_item_keys'][$cart_item]['is_variation'] = true;

2. pmw.getCartItemsFromBackend() and pmw.reconcileCartFromBackend() in src/js-src/public/pmw/functions.js merge that response into pmwDataLayer.cart_item_keys via Object.assign, overwriting the { product_id, variation_id } entries that the inline cart-fragment scrips printed on page load by includes/pixels/class-pixel-manager.php.

// includes/pixels/class-pixel-manager.php
<script>
  (window.pmwDataLayer = window.pmwDataLayer || {}).cart_item_keys            = window.pmwDataLayer.cart_item_keys || {};
  window.pmwDataLayer.cart_item_keys['<?php 
    echo esc_js( $cart_item_key );
    ?>'] = <?php 
    echo wp_json_encode( $data, $json_encode_options );
    ?>;
</script>

// src/js-src/public/pmw/functions.js</span>
if (pmwDataLayer.cart_item_keys[cartItemKey]["variation_id"] === 0) {
  productId = pmwDataLayer.cart_item_keys[cartItemKey]["product_id"];
} else {
  productId = pmwDataLayer.cart_item_keys[cartItemKey]["variation_id"];
}

3. pmw.getProductIdByCartItemKeyUrl() still reads the old fields, but since the “variation_id” key was overwritten, the productId will be undefined “variation_id” does not exist in the cart_item_keys[cartItemKey] associative array.

// product-detection.js
if (pmwDataLayer.cart_item_keys[cartItemKey]["variation_id"] === 0) {
   productId = pmwDataLayer.cart_item_keys[cartItemKey]["product_id"];
} else {
   productId = pmwDataLayer.cart_item_keys[cartItemKey]["variation_id"];
}

This explains why the “Wasn’t able to retrieve a productId” error was thrown.

Happy to provide debug logs or more details if useful. Thanks again for a fantastic plugin!

• This topic was modified 3 weeks, 2 days ago by jozbelio.
• This topic was modified 3 weeks, 2 days ago by jozbelio.