migrations: Backfill is_channel_message.

tools/semgrep-py.yml

@@ -54,6 +54,7 @@ rules:
 
   - id: dont-import-models-in-migrations
     patterns:
+      - pattern-not: from zerver.lib.migrate import $X
       - pattern-not: from zerver.lib.partial import partial
       - pattern-not: from zerver.lib.mime_types import $X
       - pattern-not: from zerver.lib.redis_utils import get_redis_client

zerver/migrations/0691_backfill_message_is_channel_message.py

@@ -0,0 +1,37 @@
+from django.db import connection, migrations
+from django.db.backends.base.schema import BaseDatabaseSchemaEditor
+from django.db.migrations.state import StateApps
+from psycopg2.sql import SQL
+
+from zerver.lib.migrate import do_batch_update
+
+
+def update_is_channel_message(apps: StateApps, schema_editor: BaseDatabaseSchemaEditor) -> None:
+    Message = apps.get_model("zerver", "Message")
+    ArchivedMessage = apps.get_model("zerver", "ArchivedMessage")
+
+    with connection.cursor() as cursor:
+        for message_model in [Message, ArchivedMessage]:
+            do_batch_update(
+                cursor,
+                message_model._meta.db_table,
+                [
+                    SQL(
+                        "is_channel_message = (SELECT type = 2 FROM zerver_recipient WHERE zerver_recipient.id = recipient_id)"
+                    )
+                ],
+            )
+
+
+class Migration(migrations.Migration):
+    atomic = False
+
+    dependencies = [
+        ("zerver", "0690_message_is_channel_message"),
+    ]
+
+    operations = [
+        migrations.RunPython(
+            update_is_channel_message, reverse_code=migrations.RunPython.noop, elidable=True
+        )
+    ]