Canvas Factory

Canvas Factory print wall art — you pick an image, pick a size, and they print and ship it. They run CS-Cart across Australian, New Zealand and US storefronts, and I was brought in to implement GA4 and Google Tag Manager ecommerce tracking across all of it.

Which sounds routine, and wasn't, because of one structural fact: the store doesn't sell products.

Selling sizes, not products

The images come from external licensing providers — Getty, Alamy and others — at a scale approaching 100,000 images. They aren't CS-Cart products. They don't have product IDs, they aren't in the catalogue, and they can't be, because the catalogue would be meaningless at that size and would need to track someone else's inventory.

What the store actually sells is a size of a print of an image. GA4's ecommerce model, meanwhile, very much wants a product with an ID and a category. So the job became designing a mapping: a composite item-ID scheme of {source}_{art_image_id} that stays stable across sessions and providers, and a category hierarchy that GA4 would accept and that the client's marketing team could actually read in a report.

Two bugs worth mentioning

An add_to_cart event that had never once fired in production. The listener existed on the upgraded site, so it worked in every environment anyone tested in. It was missing entirely from live. Nobody had noticed, because the absence of an event doesn't look like anything — the reports just quietly had a hole where the most important step of the funnel should be.

Event integrity across an iframe boundary. The canvas configurator — where the customer crops and positions their image — is an iframe maintained by a third-party developer, so events had to cross a postMessage handoff between two codebases, only one of which I controlled. Debugging that meant establishing, for each event, whether it was fired at all, fired twice, fired with the wrong payload, or fired into a listener that had already been torn down. It's a good reminder that in analytics work the bug is almost never in the analytics.

All of the tracking work shipped, and the client and marketing company involved were very happy with the results.