Bug: Migration 0006_mariadb_uuid_conversion references non-existent uuid columns in StudentItem and Score models

[cmersinli]

Description

Migration 0006_mariadb_uuid_conversion (added in v3.12.1 via PR #321) attempts to modify uuid columns in three tables, but two of those tables don't have uuid columns:

The Problem

The migration executes these SQL statements on MariaDB:

ALTER TABLE submissions_submission MODIFY uuid uuid NOT NULL    -- ✅ This column EXISTS
ALTER TABLE submissions_studentitem MODIFY uuid uuid NOT NULL   -- ❌ This column does NOT exist
ALTER TABLE submissions_score MODIFY uuid uuid NOT NULL         -- ❌ This column does NOT exist

Evidence from models.py

Looking at submissions/models.py, only these models have UUID fields:

Model	Has uuid field?
Submission	✅ Yes - line 315: uuid = models.UUIDField(...)
TeamSubmission	✅ Yes - line 128: uuid = models.UUIDField(...)
SubmissionFile	✅ Yes - line 753: uuid = models.UUIDField(...)
StudentItem	❌ No - only has student_id, course_id, item_id, item_type
Score	❌ No - only has foreign keys and score fields

Error Message

When running migrations on a fresh Open edX Ulmo installation with MariaDB:

django.db.utils.OperationalError: (1054, "Unknown column 'uuid' in 'submissions_studentitem'")
  Applying submissions.0006_mariadb_uuid_conversion...

Environment

• Open edX: Ulmo (December 2025)
• Tutor: 21.x
• edx-submissions: 3.12.1
• Database: MariaDB 10.11.x
• Django: 5.x

Suggested Fix

The migration should only modify submissions_submission table, since that's the only table with a uuid column that needs conversion:

def apply_mariadb_migration(apps, schema_editor):
    # ... MariaDB check code ...
    
    with connection.cursor() as cursor:
        # Only Submission model has uuid field
        cursor.execute(
            "ALTER TABLE submissions_submission "
            "MODIFY uuid uuid NOT NULL"
        )
        # Remove StudentItem and Score - they don't have uuid columns

Workaround

For anyone encountering this issue, you can fake the migration:

./manage.py lms migrate submissions 0006_mariadb_uuid_conversion --fake

This is safe because:

1. submissions_submission.uuid is already created as native uuid type with Django 5
2. StudentItem and Score don't have uuid columns in the model definition

Related

• PR fix: Convert UUIDField columns to uuid type for MariaDB #321 that introduced this migration
• Reference article mentioned in migration: https://www.albertyw.com/note/django-5-mariadb-uuidfield