Fix: fix broken migration in 3.0.1 (#13242)

src/paperless_mail/migrations/0001_1_clamp_mailrule_maximum_age.py

@@ -1,27 +0,0 @@
-# Split out of 0002_optimize_integer_field_sizes.py into its own migration
-# (own transaction). Running this UPDATE in the same transaction as the
-# later ALTER TABLE on paperless_mail_mailrule can fail on PostgreSQL with
-# "cannot ALTER TABLE because it has pending trigger events", since the
-# update queues FK trigger events against that table that are still pending
-# when the subsequent AlterField tries to rewrite it. Committing the clamp
-# here first avoids that.
-from django.db import migrations
-
-
-def clamp_mailrule_maximum_age(apps, schema_editor):
-    # Clamp the maximum_age field of MailRule because of PositiveIntegerField --> PositiveSmallIntegerField
-    MailRule = apps.get_model("paperless_mail", "MailRule")
-    MailRule.objects.filter(maximum_age__gt=32767).update(maximum_age=32767)
-
-
-class Migration(migrations.Migration):
-    dependencies = [
-        ("paperless_mail", "0001_squashed"),
-    ]
-
-    operations = [
-        migrations.RunPython(
-            clamp_mailrule_maximum_age,
-            migrations.RunPython.noop,
-        ),
-    ]

src/paperless_mail/migrations/0002_optimize_integer_field_sizes.py

@@ -4,9 +4,19 @@ from django.db import migrations
 from django.db import models
 
 
+def clamp_mailrule_maximum_age(apps, schema_editor):
+    # Clamp the maximum_age field of MailRule because of PositiveIntegerField --> PositiveSmallIntegerField
+    MailRule = apps.get_model("paperless_mail", "MailRule")
+    MailRule.objects.filter(maximum_age__gt=32767).update(maximum_age=32767)
+
+
 class Migration(migrations.Migration):
+    # The data update must commit before PostgreSQL rewrites the table, otherwise
+    # pending foreign-key trigger events can block the subsequent ALTER TABLE.
+    atomic = False
+
     dependencies = [
-        ("paperless_mail", "0001_1_clamp_mailrule_maximum_age"),
+        ("paperless_mail", "0001_squashed"),
     ]
 
     operations = [
@@ -112,6 +122,10 @@ class Migration(migrations.Migration):
                 verbose_name="consumption scope",
             ),
         ),
+        migrations.RunPython(
+            clamp_mailrule_maximum_age,
+            migrations.RunPython.noop,
+        ),
         migrations.AlterField(
             model_name="mailrule",
             name="maximum_age",

src/paperless_mail/tests/test_migrations.py

@@ -0,0 +1,37 @@
+import importlib
+
+from django.db import migrations
+
+
+def test_optimize_integer_fields_preserves_released_migration_history():
+    migration_module = importlib.import_module(
+        "paperless_mail.migrations.0002_optimize_integer_field_sizes",
+    )
+
+    assert migration_module.Migration.dependencies == [
+        ("paperless_mail", "0001_squashed"),
+    ]
+
+
+def test_mailrule_maximum_age_is_clamped_before_non_atomic_alter():
+    migration_module = importlib.import_module(
+        "paperless_mail.migrations.0002_optimize_integer_field_sizes",
+    )
+    migration = migration_module.Migration
+
+    clamp_index = next(
+        index
+        for index, operation in enumerate(migration.operations)
+        if isinstance(operation, migrations.RunPython)
+        and operation.code is migration_module.clamp_mailrule_maximum_age
+    )
+    alter_index = next(
+        index
+        for index, operation in enumerate(migration.operations)
+        if isinstance(operation, migrations.AlterField)
+        and operation.model_name == "mailrule"
+        and operation.name == "maximum_age"
+    )
+
+    assert migration.atomic is False
+    assert clamp_index < alter_index