Tracking Coupon codes from Commerce Promotions

Drupal Commerce has a coupon reference field on orders that stores which coupons have been applied to the order. It's not an exact match to Google's data model, which appears to expect a single coupon, but we can grab the first one and add it to the purchase event template in:

https://git.drupalcode.org/project/google_tag/-/blob/2.0.x/src/Plugin/Go...

Would be nice if one of the options I've tagged into the "Deprecate Commerce GTM" list could be used to give merchants the opportunity to alter which coupon code gets used in the event of there being more than one. We could always sort them by their relative promotion sort orders so there's at least a consistent default with some UI based influence.

I created a MR with simply adding the coupon code to the dataLayer.

Thanks kaszarobert - can I add your commit into my composer.json - or do we need a .patch file for that?

@newaytech usually you add patch files to composer.json because the feature branch used for MR could change in the meantime if further changes will be required by reviewers. A patch file will stay the same. I uploaded a static patch file with the same modifications as in MR.

Thanks kaszarobert - I've applied your patch via composer.json - works a treat - and we're now tracking promo codes in GA4 via GTM - fantastic!

@newaytech - I've applied the patch but do not know how to configure GTM to track the codes.

Can you share how you configured GTM/GA4?

Thanks.

If you're using google_tag module's latest version, then create a new data layer variable in GTM called "Ecommerce Coupon" with value as eventModel.coupon and for the GA 4 purchase tag under Event parameters (where you add items, transaction_id, value, currency etc.) add a new row with "coupon" and "{{Ecommerce Coupon}}"

Thanks @kaszarobert!

I used eventModel.coupon for the Ecommerce Coupon value.

For items and transaction_id, should I do the same like this...

eventModel.items
eventModel.transaction_id

or should they be...

ecommerce.items
ecommerce.transaction_id

Open the Preview in GTM and check it. That's the most reliable way.

It really depends on how you send it. For example take a look at the add_to_cart event with the newest Google Tag module version does it this way in the dataLayer JS variable:

[
...
{
    "0": "event",
    "1": "add_to_cart",
    "2": {
        "currency": "EUR",
        "value": "10.00",
        "items": [
            {
                "item_name": "Product1",
                "affiliation": "Shop",
                "price": "10.00",
                "quantity": 1,
                "item_id": "ProductSku"
            }
        ]
    }
}
...
]

So there's no ecommerce key, just the items, so we use eventModel.items

The older Commerce Google Tag module used to do it this way:

[
...
{
    "event": "add_to_cart",
    "ecommerce": {
        "items": [
            {
                "item_name": "Product1",
                "item_id": "ProductSku",
                "price": "10.00",
                "item_variant": "ProductSku",
                "currency": "EUR",
                "quantity": 1
            }
        ]
    },
    "gtm.uniqueEventId": 6
}
...
]

There we used to have an ecommerce key and under it were the settings, so we had to use ecommerce.items. So please check it on GTM Preview if the variables from the dataLayer are set properly. And that goes for purchase and any other ecommerce events, too. But if you are using this module's 2.x.x version, then I think the first one will be the one that works.

Thank you for the details and differences. I'm using the 2.x.x version (newest), so I'll review the first example you shared.

I attach my Event params - passed to the GA4 purchase event - and also the debug of the dataLayer as seen on the receipt page (using the patch in #7) - in the screenshot attached.