@SeverinEventfrog opened this Issue on October 28th 2022

We run a webshop. Users can put items in their basket and stroll around, but only need to login with a userId when starting the checkout proceedure. We want to have all actions pre-login also assigned to the userId. However, when enable_userid_overwrites_visitorid = 1 is set (is by default), then Matomo will not find the existing visit pre-login and instead create a new visit for the userId. Thereby loosing a lot of user interactions, like looking at products and not buying them.

Expected Behavior

enable_userid_overwrites_visitorid = 1
Navigate to the home page
1 visit with 1 action with unknown user
Navigate to the login screen
1 visit with 2 actions with unknow user
Login and call setUserId function
1 visit with 3 actions with known user (merging all pass actions)
Logout
1 visit with 4 actions with know user (it continues to put actions in the same visit)

Current Behavior

enable_userid_overwrites_visitorid = 1
Navigate to the home page without any Cookie
1 visit with 1 action with unknown user
Navigate to the login screen
1 visit with 2 actions with unknow user
Login and call setUserId function
1 visit with 2 actions with unknown user
1 visit with 1 action with known user (it didn't merged the pass actions)
Logout and no longer use setUserId
1 visit with 3 actions with unknow user
1 visit with 1 action with known user

Possible Solution

When userId overwrites visitorId, the check for existing visits should also check for visits of the visitorId, if that one is supplied. As when the visitorId is supplied, the trackingrequest clearly states to be from that visitor. So claiming the visit with the newly supplied userID is expected behaviour and even documented here: https://matomo.org/faq/general/how-are-requests-with-a-user-id-tracked/
"When a user logs in, Matomo counts all actions before and after logging in as one user, one visit, and one unique visitor."

Inuitively, this check could be done only, if no active visit for the userId is found.
However, I would suggest claiming the given visit even if another already assigned to the userId exists, as they might be from different devices within 20 minutes and just adding to the older one would disconnect the newer visits's previous actions from the userId.

Pseudocode:
get_existing_visit(visitorId, userId){
visits.add(get_visits_by_visitorId(visitorId)) # make sure, that visitorId has not already been overwriten by userId!
visits.add(get_visits_by_userId(userId))
visits.sort_by_last_action_time()
return visits.pop()
}

Steps to Reproduce (for Bugs)

See Behavior, we use JavaScript Tracking and the _paq.push(['setUserId', 'USER_ID_HERE']);

Context

In our Webshop, we want to know what a user has looked at and done during one sitting. If they happen to log in, we want all their actions to be mapped to their userID. We want this mapping to work, even if the user deletes their Cookies. We also want to be able to use the Matomo UI to click on Visitor-Profile and see all past actions of that User ( not only Visitor!).

We are aware of this option:
enable_userid_overwrites_visitorid = 0
Navigate to the home page
1 visit with 1 action with unknown user
Navigate to the login screen
1 visit with 2 actions with unknow user
Login and call setUserId function
1 visit with 3 actions with known user (just setting userID, vistorID unchanged)
Logout
1 visit with 4 actions with know user (it continued to put actions in the same visit)
But then, should the user ever delete their Cookie or much more likely just use another device, they would get another visitorID. The userID link is our active workaround but is slow for DB SELECTS and the Matomo Admin UI will only show all actions of the same VisitorID and not userID.

Your Environment

  • Matomo Version: 4.10.0
  • PHP Version: 7.3
  • Server Operating System: Debian 4.19.x
  • Additionally installed plugins:
    FormAnalytics
    GoogleAnalyticsImporter
    HeatmapSessionRecording
    MediaAnalytics

For information:

Matomo 4.1.0 on Windows
Edge 87 without adblocker
@bx80 commented on October 30th 2022 Contributor

Thanks for reporting this @SeverinEventfrog, the detail you've provided is very helpful :+1:

Since this is a case of documented behavior no longer happening in the current release I'll mark this as a regression.

@janinaMi commented on November 21st 2022

Hey, im expiriencing the same issue. Could you please prioritize the issue higher, because it really messes up the tracking data.
Maybe it would be a possibility for the matching in the isNewVisit() method to use not only the user-id generated visitor-id, but also the visitor-id, which would be active without user-id?

@bx80 commented on November 28th 2022 Contributor

@mattab This appears to be the same issue as L3-265. Since it's a regression, should it be assigned to the next point release?

@sgiehl commented on November 30th 2022 Member

@SeverinEventfrog @janinaMi Are you only using the setUserId method when the user logs in, or does this also trigger something else, like setCookieConsentGiven or enableBrowserFeatureDetection?

@janinaMi commented on November 30th 2022

@sgiehl I'm just using the setUserId method

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