Amazon\Pay\Model\CustomerManagement::setAmazonIdExtensionAttribute - Caching does not handle missing amazon user (Remains null)

[steven-hoffman-jomashop]

What I expected

For Amazon\Pay\Model\CustomerManagement::setAmazonIdExtensionAttribute:

• $this->customerLinkManagement->getByCustomerId($customer->getId()); is only called once (Per customer).

What happened instead

• $this->customerLinkManagement->getByCustomerId($customer->getId()); returns an empty object
• $amazonCustomer->getId() as false
• $this->amazonId remains null

Steps to reproduce the issue

Call into Amazon\Pay\Model\CustomerManagement::setAmazonIdExtensionAttribute multiple times.

Possible Fix

• Set $this->amazonId to something non-null that is falsy (0, '', false)
• Then it will not load and will not set the value to the extension attribute

Your setup

• Version should not matter
  • https://github.com/amzn/amazon-payments-magento-2-plugin/blob/5.18.0/Model/CustomerManagement.php
  • Has no significant changes in a few years.

[sgabhart22]

Hi @steven-hoffman-jomashop ,

Does this manifest in the shopper's experience somehow, and if so, could you please provide an example? e.g., duplicated quotes, cart being emptied unexpectedly, etc. A few more details would help us debug and remediate more effectively.

Thanks, Spencer

[steven-hoffman-jomashop]

Hi @sgabhart22,

This would not 'manifest' to the customer; aside from a slower response time. The issue is that the caching logic does not 'consider' a null response as a 'cachable' response. As such the caching logic does not handle a missing 'customer link' and will repeat the query to the database if the same customer model is requested again.

In Summary, this is a performance issue, not a bug in 'behavior'.