Proposal - Add in hook alterPostIpn or similar
As discussed in Mattermost https://chat.civicrm.org/civicrm/pl/xt83abz75pbwtr5k4em4thhp1r the proposal is to add in a hook like hook_civicrm_alterIPNData or similar that would allow developers to utilise data that comes back in via IPNs especially in this case PayPal.
The usecase here is that we would use the AlterPaymentProcessorParams hook to include a googleAnalytics token which includes utm codes etc, then use the alterIPNData hook to then extract that when the IPN is processed by CiviCRM sending a GA event so that when the transaction is recorded the UTM codes etc that were associated with the link are also passed up to GA so we can link back to the original hit on the site that the IPN relates to.
I plan to leave this for about a week for people to comment if no objections raised then i will work on writing the hook,
@jamienovick1 @JoeMurray @justinfreeman @mattwire @eileen et all