Files
zulip/zerver/migrations/0074_fix_duplicate_attachments.py
Aman Agrawal 47bf111de8 migrations: Mark RunPython statements elidable.
This will make django automatically remove them when we run
squashmigrations. There are still some RunSQL statements which
we will have to take care of manually.
2020-04-29 10:41:20 -07:00

46 lines
2.0 KiB
Python

# Generated by Django 1.10.5 on 2017-04-13 22:12
from django.db import migrations
from django.db.backends.postgresql.schema import DatabaseSchemaEditor
from django.db.migrations.state import StateApps
from django.db.models import Count
def fix_duplicate_attachments(apps: StateApps, schema_editor: DatabaseSchemaEditor) -> None:
"""Migration 0041 had a bug, where if multiple messages referenced the
same attachment, rather than creating a single attachment object
for all of them, we would incorrectly create one for each message.
This results in exceptions looking up the Attachment object
corresponding to a file that was used in multiple messages that
predate migration 0041.
This migration fixes this by removing the duplicates, moving their
messages onto a single canonical Attachment object (per path_id).
"""
Attachment = apps.get_model('zerver', 'Attachment')
# Loop through all groups of Attachment objects with the same `path_id`
for group in Attachment.objects.values('path_id').annotate(Count('id')).order_by().filter(id__count__gt=1):
# Sort by the minimum message ID, to find the first attachment
attachments = sorted(list(Attachment.objects.filter(path_id=group['path_id']).order_by("id")),
key = lambda x: min(x.messages.all().values_list('id')[0]))
surviving = attachments[0]
to_cleanup = attachments[1:]
for a in to_cleanup:
# For each duplicate attachment, we transfer its messages
# to the canonical attachment object for that path, and
# then delete the original attachment.
for msg in a.messages.all():
surviving.messages.add(msg)
surviving.is_realm_public = surviving.is_realm_public or a.is_realm_public
surviving.save()
a.delete()
class Migration(migrations.Migration):
dependencies = [
('zerver', '0073_custom_profile_fields'),
]
operations = [
migrations.RunPython(fix_duplicate_attachments, elidable=True)
]