客户端到服务器端Google Analytics MP客户端ID

Question

I am trying to send transaction data to UA from a webshop which is only creating orders once it has received a "push" from a payment processing API. A success page is displayed to the customer independently from the order being created, meaning the tracking script (UA via GTM with data layer) does not have access to the order data.

This gives me the headache of trying to track transactions made through the webshop server side, instead of client side. Yet I still want to tie the transaction to the unique visitor ID who made the purchase, not just a random Client ID each time.

My site is using analyics.js (UA profile). Therefore I thought somewhere a client ID would be stored as a cookie, and I do see a _ga cookie there which I believe is the client ID, which looks like this:

GA1.2.1586737968.1429871710 

The documentation for getting cookie and user identification states the following:

You should not directly access the cookie analytics.js sets, as the cookie format might change in the future. Instead, developers should use the readyCallback to wait until analytics.js is loaded, and then get the clientId value stored on the tracker.

... which is not helpful to me, as I have to do this server side. But anyway, this client ID does not even fit the description of what a client ID looks like , although it does appear to match a legacy format . Sort of.

Couple of questions then:

1. Is it just those last two numbers 1586737968.1429871710 that I need to be parsing from the _ga cookie and sending as a client ID? Or is the whole thing ok?
2. Are there any scripts/libraries that will do this for me so I don't have have to worry about Google suddenly giving new visitors the client ID based on the new UUID v4 format?
3. Does this approach have any obvious flaws?

Answer 1

Answers:

1. Yes the cid value should just be the last 2 numbers as you rightly point out. (this is experience from client setups that already successfully use Measurement Protocol on an ongoing basis)
2. Nope, not as far as I am aware, best to do it yourself. It will only be a few lines of code to detect what format you're seeing in the cookie and what, therefore you need to send through.
3. not really. It is a common enough scenario.