Disclaimer: I am not a professional programmer. There may be better ways to go about this, but the following solution has worked for me.
Implementing e-commerce tracking for paypal users is a two step process:
1a: modify your paypal buy now form as follows:
- If you haven’t already, give the form a name.
1c: Modify the standard Piwik JS tracking code to also grab the visitorID, etc. from Piwik, and forward it via paypal.
Notice that I’ve taken my existing data that I was already passing via Paypal’s custom var, and appended the piwik data, using ampersands as a delimiter.
Next post will show Step 2: modifying your IPN script.