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47bf111de8
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.
46 lines
2.0 KiB
Python
46 lines
2.0 KiB
Python
# Generated by Django 1.10.5 on 2017-04-13 22:12
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from django.db import migrations
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from django.db.backends.postgresql.schema import DatabaseSchemaEditor
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from django.db.migrations.state import StateApps
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from django.db.models import Count
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def fix_duplicate_attachments(apps: StateApps, schema_editor: DatabaseSchemaEditor) -> None:
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"""Migration 0041 had a bug, where if multiple messages referenced the
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same attachment, rather than creating a single attachment object
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for all of them, we would incorrectly create one for each message.
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This results in exceptions looking up the Attachment object
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corresponding to a file that was used in multiple messages that
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predate migration 0041.
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This migration fixes this by removing the duplicates, moving their
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messages onto a single canonical Attachment object (per path_id).
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"""
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Attachment = apps.get_model('zerver', 'Attachment')
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# Loop through all groups of Attachment objects with the same `path_id`
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for group in Attachment.objects.values('path_id').annotate(Count('id')).order_by().filter(id__count__gt=1):
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# Sort by the minimum message ID, to find the first attachment
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attachments = sorted(list(Attachment.objects.filter(path_id=group['path_id']).order_by("id")),
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key = lambda x: min(x.messages.all().values_list('id')[0]))
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surviving = attachments[0]
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to_cleanup = attachments[1:]
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for a in to_cleanup:
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# For each duplicate attachment, we transfer its messages
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# to the canonical attachment object for that path, and
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# then delete the original attachment.
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for msg in a.messages.all():
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surviving.messages.add(msg)
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surviving.is_realm_public = surviving.is_realm_public or a.is_realm_public
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surviving.save()
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a.delete()
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class Migration(migrations.Migration):
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dependencies = [
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('zerver', '0073_custom_profile_fields'),
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]
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operations = [
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migrations.RunPython(fix_duplicate_attachments, elidable=True)
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]
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