Opened 32 hours ago

Last modified 30 hours ago

#35967 new Bug

TransactionTestCase.serialized_rollback reads from real database rather than test when using read replica for a model instance created in a migration with a ManyToManyField

Reported by: Jake Howard Owned by:
Component: Database layer (models, ORM) Version: dev
Severity: Normal Keywords:
Cc: Ryan Cheley Triage Stage: Unreviewed
Has patch: no Needs documentation: no
Needs tests: no Patch needs improvement: no
Easy pickings: no UI/UX: no

Description

(Yes, this is a rather specific bug...)

When:

  1. Using a database router to create a read-replica database, configured as a MIRROR in tests, and
  2. Using TransactionTestCase.serialized_rollback, and
  3. Having a model instance created in a migration which has a ManyToMany field

The serializer for serialized_rollback tries to read from the non-test database. If that database doesn't exist yet (for example, in CI), this throws an error:

django.db.utils.OperationalError: no such table: auth_user

If migrations are run (manage.py migrate), thus creating the tables for the non-test database, tests pass correctly. Prooving it's reading from the wrong connection.

I've created a ​minimal reproduction of this issue, and confirmed it happens on SQLite, PostgreSQL and Django 4.2, 5.0, 5.1 and main

Change History (1)

comment:1 by Ryan Cheley, 30 hours ago

Cc: Ryan Cheley added
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