Linking a PHP Post event to a real user
1st post, be kind!
I have been using the doc from here https://developers.google.com/analytics/devguides/collection/protocol/v1/ to create a PHP Post request for an e-commerce transactions.
Presumably this request will be unaware of the real user's data, e.g. where they came from and therefore GA will not be able to link their source with the e-commerce transaction?
How can I send additional data with the Post request in order to ensure that the user is linked to their source and other page view data.