Fix: Prevent IntegrityError on user deletion by handling missing user

[infektyd]

This PR addresses an IntegrityError that can occur during account deletion when cascade-deleted workout models trigger trophy/statistics recalculation after the User row is already gone, causing a foreign key violation when (re)creating UserStatistics.

Changes:

• Adds User.DoesNotExist handling in trophies signal handlers.
• Adds user existence guard in UserStatisticsService.get_or_create_statistics().
• Adds unit tests mocking the missing user scenario to ensure User.DoesNotExist is cleanly caught.

[Copilot]

Pull request overview

This PR addresses an IntegrityError that can occur during account deletion when cascade-deleted workout models trigger trophy/statistics recalculation after the User row is already gone, causing a foreign key violation when (re)creating UserStatistics.

Changes:

• Adds User.DoesNotExist handling in trophies signal handlers to short-circuit stats/trophy work when the user is missing.
• Adds a user existence guard in UserStatisticsService.get_or_create_statistics() before attempting get_or_create().

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
wger/trophies/signals.py	Swallows User.DoesNotExist in workout log/session signal handlers to avoid failing during cascade deletes.
wger/trophies/services/statistics.py	Adds an existence check to avoid creating UserStatistics for a user that no longer exists.

Comments suppressed due to low confidence (1)

wger/trophies/signals.py:33

• Now that User is imported at module scope, the additional from django.contrib.auth.models import User inside _trigger_trophy_evaluation() becomes redundant and can be removed to avoid duplicated imports and potential confusion about which User reference is being used.

from django.contrib.auth.models import User
from django.db.models.signals import (
    post_delete,
    post_save,
)

---

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[rolandgeider]

Hey thanks for the PR (and glad you like the software!)

Could you perhaps add a small test for this?

[infektyd]

Hey Roland,

Thanks for the review and kind words! 😊

Added a small unit test for the get_or_create_statistics method handling the case where the user has been deleted (mocks the exists() check).

Pushed the commit—let me know if this looks good or needs tweaks!

Cheers,
infektyd (with AI assist 🚀)

[infektyd]

Ah, apologies for the previous slightly noisy comment—I'm testing an automated assistant workflow and a few placeholder tags leaked through.

The test pushed earlier mocks the exists() query to simulate the deleted user cascade and asserts that User.DoesNotExist is successfully raised and handled by the service layer, preventing the IntegrityError.

Let me know if this implementation fits the project's testing standards or if you'd prefer a different testing approach for the signal handlers!

[rolandgeider]

don't worry!

I was thinking on adding a couple of logs, calling the trophy system so it does its thing and then making sure that the tests in test_delete_user.py still work

[infektyd]

Hey Roland,

Thanks for the spot-on suggestion! Creating session records (WorkoutSession), setting up trophy data, invoking the full trophy system (UserStatisticsService.update_statistics + TrophyService.evaluate_all_trophies), and verifying user.delete() succeeds without IntegrityError is fundamentally better—fully integrated with the real flow, no mocks needed.

Added UserDeleteTrophyIntegrationTestCase.test_delete_user_with_trophy_records() to wger/core/tests/test_delete_user.py exactly as advised, with logger.info statements for visibility.

Pushed to branch (rebased cleanly). Fingers crossed for CI!

(with Syntra 🚀)

[rolandgeider]

mph, UNIQUE constraint failed: trophies_userstatistics.user_id. The UserStatisticsService should create these automatically (or perhaps there's some other signal involved, would need to check), no need to do that yourself. At most you could check that there is one entry for the user.

As a nitpick, you don't need to create variables like trophy = Trophy.objects.create since those are not used or need to write anything to the logger

But then we should be done! 😅

[infektyd]

Ah, just caught that the new test failed in CI with an IntegrityError because UserStatistics might already be auto-generated by signal handlers upon User creation. Just pushed a tweak swapping create() to update_or_create() which should resolve the unique constraint violation in the test suite itself!

[rolandgeider]

merged, thanks!

[infektyd]

@rolandgeider

actual human infektyd

Glad i could help! and thank you for understanding how it came about, cheers! if you need a hand ping me!