Files
zulip/zerver/migrations/0074_fix_duplicate_attachments.py
Anders Kaseorg df001db1a9 black: Reformat with Black 23.
Black 23 enforces some slightly more specific rules about empty line
counts and redundant parenthesis removal, but the result is still
compatible with Black 22.

(This does not actually upgrade our Python environment to Black 23
yet.)

Signed-off-by: Anders Kaseorg <anders@zulip.com>
2023-02-02 10:40:13 -08:00

53 lines
2.1 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 BaseDatabaseSchemaEditor
from django.db.migrations.state import StateApps
from django.db.models import Count
def fix_duplicate_attachments(apps: StateApps, schema_editor: BaseDatabaseSchemaEditor) -> 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(
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),
]