TadrisinoTokenAuthentication ran one SELECT on accounts_user for every
authenticated request. Off by default (AUTH_USER_CACHE_TTL=0) so behaviour
is unchanged until a deployment opts in.
accounts/authentication.py
- _get_request_user(): when AUTH_USER_CACHE_TTL>0, cache all concrete
field values under auth:user:<id> and rebuild a full User instance
(so save(update_fields=[...]) stays safe); otherwise load from DB as
before. invalidate_user_cache() / _load_user_or_fail() helpers.
accounts/receivers.py (new)
- post_save/post_delete on User -> invalidate_user_cache(pk); covers
every in-app write path (SetUserGrade, login, refresh, last_activity).
accounts/apps.py
- AccountsConfig.ready() imports receivers.
accounts/tests.py
- AuthUserRowCacheTests: disabled -> loads every request; enabled ->
loads once then cache; User.save() invalidates; SetUserGradeView still
persists and the next request sees the new grade.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
