From e67d7d70fa10c06aca36b9057f82054eda45269d Mon Sep 17 00:00:00 2001 From: Simon Charette Date: Sun, 28 Jan 2024 12:02:33 -0500 Subject: [PATCH] Fixed #35149 -- Fixed crashes of db_default with unresolvable output field. Field.db_default accepts either literal Python values or compilables (as_sql) and wrap the former ones in Value internally. While 1e38f11 added support for automatic resolving of output fields for types such as str, int, float, and other unambigous ones it's cannot do so for all types such as dict or even contrib.postgres and contrib.gis primitives. When a literal, non-compilable, value is provided it likely make the most sense to bind its output field to the field its attached to avoid forcing the user to provide an explicit `Value(output_field)`. Thanks David Sanders for the report. --- django/db/backends/base/schema.py | 7 +++---- django/db/models/fields/__init__.py | 21 +++++++++++++-------- docs/releases/5.0.2.txt | 5 +++++ tests/migrations/test_autodetector.py | 4 ++-- tests/migrations/test_operations.py | 12 ++++++------ tests/schema/tests.py | 21 +++++++++++++++++++++ 6 files changed, 50 insertions(+), 20 deletions(-) diff --git a/django/db/backends/base/schema.py b/django/db/backends/base/schema.py index ed91c6ab1b4..f442d290a00 100644 --- a/django/db/backends/base/schema.py +++ b/django/db/backends/base/schema.py @@ -412,14 +412,13 @@ class BaseDatabaseSchemaEditor: """Return the sql and params for the field's database default.""" from django.db.models.expressions import Value + db_default = field._db_default_expression sql = ( - self._column_default_sql(field) - if isinstance(field.db_default, Value) - else "(%s)" + self._column_default_sql(field) if isinstance(db_default, Value) else "(%s)" ) query = Query(model=field.model) compiler = query.get_compiler(connection=self.connection) - default_sql, params = compiler.compile(field.db_default) + default_sql, params = compiler.compile(db_default) if self.connection.features.requires_literal_defaults: # Some databases doesn't support parameterized defaults (Oracle, # SQLite). If this is the case, the individual schema backend diff --git a/django/db/models/fields/__init__.py b/django/db/models/fields/__init__.py index 5186f0c414d..cc5025af84b 100644 --- a/django/db/models/fields/__init__.py +++ b/django/db/models/fields/__init__.py @@ -219,12 +219,6 @@ class Field(RegisterLookupMixin): self.remote_field = rel self.is_relation = self.remote_field is not None self.default = default - if db_default is not NOT_PROVIDED and not hasattr( - db_default, "resolve_expression" - ): - from django.db.models.expressions import Value - - db_default = Value(db_default) self.db_default = db_default self.editable = editable self.serialize = serialize @@ -408,7 +402,7 @@ class Field(RegisterLookupMixin): continue connection = connections[db] - if not getattr(self.db_default, "allowed_default", False) and ( + if not getattr(self._db_default_expression, "allowed_default", False) and ( connection.features.supports_expression_defaults ): msg = f"{self.db_default} cannot be used in db_default." @@ -994,7 +988,7 @@ class Field(RegisterLookupMixin): from django.db.models.expressions import DatabaseDefault if isinstance(value, DatabaseDefault): - return self.db_default + return self._db_default_expression return value def get_prep_value(self, value): @@ -1047,6 +1041,17 @@ class Field(RegisterLookupMixin): return return_None return str # return empty string + @cached_property + def _db_default_expression(self): + db_default = self.db_default + if db_default is not NOT_PROVIDED and not hasattr( + db_default, "resolve_expression" + ): + from django.db.models.expressions import Value + + db_default = Value(db_default, self) + return db_default + def get_choices( self, include_blank=True, diff --git a/docs/releases/5.0.2.txt b/docs/releases/5.0.2.txt index a385fbd13ef..6312dee3127 100644 --- a/docs/releases/5.0.2.txt +++ b/docs/releases/5.0.2.txt @@ -36,3 +36,8 @@ Bugfixes * Fixed a bug in Django 5.0 that caused a migration crash on MySQL when adding a ``BinaryField``, ``TextField``, ``JSONField``, or ``GeometryField`` with a ``db_default`` (:ticket:`35162`). + +* Fixed a bug in Django 5.0 that caused a migration crash on models with a + literal ``db_default`` of a complex type such as ``dict`` instance of a + ``JSONField``. Running ``makemigrations`` might generate no-op ``AlterField`` + operations for fields using ``db_default`` (:ticket:`35149`). diff --git a/tests/migrations/test_autodetector.py b/tests/migrations/test_autodetector.py index c54349313e7..340805b2598 100644 --- a/tests/migrations/test_autodetector.py +++ b/tests/migrations/test_autodetector.py @@ -1309,7 +1309,7 @@ class AutodetectorTests(BaseAutodetectorTests): changes, "testapp", 0, 0, name="name", preserve_default=True ) self.assertOperationFieldAttributes( - changes, "testapp", 0, 0, db_default=models.Value("Ada Lovelace") + changes, "testapp", 0, 0, db_default="Ada Lovelace" ) @mock.patch( @@ -1515,7 +1515,7 @@ class AutodetectorTests(BaseAutodetectorTests): changes, "testapp", 0, 0, name="name", preserve_default=True ) self.assertOperationFieldAttributes( - changes, "testapp", 0, 0, db_default=models.Value("Ada Lovelace") + changes, "testapp", 0, 0, db_default="Ada Lovelace" ) @mock.patch( diff --git a/tests/migrations/test_operations.py b/tests/migrations/test_operations.py index 5733ba76186..f25bb290a58 100644 --- a/tests/migrations/test_operations.py +++ b/tests/migrations/test_operations.py @@ -1581,7 +1581,7 @@ class OperationTests(OperationTestBase): self.assertEqual(len(new_state.models[app_label, "pony"].fields), 6) field = new_state.models[app_label, "pony"].fields["height"] self.assertEqual(field.default, models.NOT_PROVIDED) - self.assertEqual(field.db_default, Value(4)) + self.assertEqual(field.db_default, 4) project_state.apps.get_model(app_label, "pony").objects.create(weight=4) self.assertColumnNotExists(table_name, "height") # Add field. @@ -1632,7 +1632,7 @@ class OperationTests(OperationTestBase): self.assertEqual(len(new_state.models[app_label, "pony"].fields), 6) field = new_state.models[app_label, "pony"].fields["special_char"] self.assertEqual(field.default, models.NOT_PROVIDED) - self.assertEqual(field.db_default, Value(db_default)) + self.assertEqual(field.db_default, db_default) self.assertColumnNotExists(table_name, "special_char") with connection.schema_editor() as editor: operation.database_forwards( @@ -1700,7 +1700,7 @@ class OperationTests(OperationTestBase): self.assertEqual(len(new_state.models[app_label, "pony"].fields), 6) field = new_state.models[app_label, "pony"].fields["height"] self.assertEqual(field.default, 3) - self.assertEqual(field.db_default, Value(4)) + self.assertEqual(field.db_default, 4) pre_pony_pk = ( project_state.apps.get_model(app_label, "pony").objects.create(weight=4).pk ) @@ -2145,7 +2145,7 @@ class OperationTests(OperationTestBase): old_weight = project_state.models[app_label, "pony"].fields["weight"] self.assertIs(old_weight.db_default, models.NOT_PROVIDED) new_weight = new_state.models[app_label, "pony"].fields["weight"] - self.assertEqual(new_weight.db_default, Value(4.5)) + self.assertEqual(new_weight.db_default, 4.5) with self.assertRaises(IntegrityError), transaction.atomic(): project_state.apps.get_model(app_label, "pony").objects.create() # Alter field. @@ -2187,7 +2187,7 @@ class OperationTests(OperationTestBase): self.assertIs(old_pink.db_default, models.NOT_PROVIDED) new_pink = new_state.models[app_label, "pony"].fields["pink"] self.assertIs(new_pink.default, models.NOT_PROVIDED) - self.assertEqual(new_pink.db_default, Value(4)) + self.assertEqual(new_pink.db_default, 4) pony = project_state.apps.get_model(app_label, "pony").objects.create(weight=1) self.assertEqual(pony.pink, 3) # Alter field. @@ -2217,7 +2217,7 @@ class OperationTests(OperationTestBase): old_green = project_state.models[app_label, "pony"].fields["green"] self.assertIs(old_green.db_default, models.NOT_PROVIDED) new_green = new_state.models[app_label, "pony"].fields["green"] - self.assertEqual(new_green.db_default, Value(4)) + self.assertEqual(new_green.db_default, 4) old_pony = project_state.apps.get_model(app_label, "pony").objects.create( weight=1 ) diff --git a/tests/schema/tests.py b/tests/schema/tests.py index 04ad299aa63..ced3367f002 100644 --- a/tests/schema/tests.py +++ b/tests/schema/tests.py @@ -7,6 +7,7 @@ from unittest import mock from django.core.exceptions import FieldError from django.core.management.color import no_style +from django.core.serializers.json import DjangoJSONEncoder from django.db import ( DatabaseError, DataError, @@ -2333,6 +2334,26 @@ class SchemaTests(TransactionTestCase): with connection.schema_editor() as editor, self.assertNumQueries(0): editor.alter_field(Author, Author._meta.get_field("name"), new_field) + @isolate_apps("schema") + def test_db_default_output_field_resolving(self): + class Author(Model): + data = JSONField( + encoder=DjangoJSONEncoder, + db_default={ + "epoch": datetime.datetime(1970, 1, 1, tzinfo=datetime.timezone.utc) + }, + ) + + class Meta: + app_label = "schema" + + with connection.schema_editor() as editor: + editor.create_model(Author) + + author = Author.objects.create() + author.refresh_from_db() + self.assertEqual(author.data, {"epoch": "1970-01-01T00:00:00Z"}) + @skipUnlessDBFeature( "supports_column_check_constraints", "can_introspect_check_constraints" )