#34946: Adding a field with default and db_default drops database level DEFAULT
-------------------------------------------+--------------------------
Reporter: Simon Charette | Owner: nobody
Type: Bug | Status: assigned
Component: Migrations | Version: 5.0
Severity: Release blocker | Keywords:
Triage Stage: Unreviewed | Has patch: 0
Needs documentation: 0 | Needs tests: 0
Patch needs improvement: 0 | Easy pickings: 0
UI/UX: 0 |
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[https://docs.djangoproject.com/en/dev/ref/models/fields/#db-default The
documentation] for `Field.db_default` states
> If both `db_default` and `Field.default` are set, `default` will take
precedence when creating instances in Python code. `db_default` will still
be set at the database level and will be used when inserting rows outside
of the ORM or when adding a new field in a migration.
However adding a field with both results in the following SQL
{{{#!sql
ALTER TABLE "foo" ADD COLUMN "bar" integer DEFAULT 42 NOT NULL;
ALTER TABLE "foo" ALTER COLUMN "bar" DROP DEFAULT;
}}}
The `DEFAULT` should never be dropped if the field has a `db_default`
defined.
The following patch reproduces and demonstrate
[https://github.com/django/django/commit/7414704e88d73dafbcfbb85f9bc54cb6111439d3
#diff-
7cc40f1cb85a8f19c80b2e901626d78e4729047dbbb0ed52861f5894ff688115R1673-R1716
why the test] that intended to cover this case didn't catch it.
{{{#!diff
diff --git a/tests/migrations/test_operations.py
b/tests/migrations/test_operations.py
index d58da8b7ac..57a9086c19 100644
--- a/tests/migrations/test_operations.py
+++ b/tests/migrations/test_operations.py
@@ -1692,15 +1692,22 @@ def test_add_field_both_defaults(self):
field = new_state.models[app_label, "pony"].fields["height"]
self.assertEqual(field.default, 3)
self.assertEqual(field.db_default, Value(4))
- project_state.apps.get_model(app_label,
"pony").objects.create(weight=4)
+ pre_pony_pk = (
+ project_state.apps.get_model(app_label,
"pony").objects.create(weight=4).pk
+ )
self.assertColumnNotExists(table_name, "height")
# Add field.
with connection.schema_editor() as editor:
operation.database_forwards(app_label, editor, project_state,
new_state)
self.assertColumnExists(table_name, "height")
+ post_pony_pk = (
+ project_state.apps.get_model(app_label,
"pony").objects.create(weight=10).pk
+ )
new_model = new_state.apps.get_model(app_label, "pony")
- old_pony = new_model.objects.get()
- self.assertEqual(old_pony.height, 4)
+ pre_pony = new_model.objects.get(pk=pre_pony_pk)
+ self.assertEqual(pre_pony.height, 4)
+ post_pony = new_model.objects.get(pk=post_pony_pk)
+ self.assertEqual(post_pony.height, 4)
new_pony = new_model.objects.create(weight=5)
if not connection.features.can_return_columns_from_insert:
new_pony.refresh_from_db()
diff --git a/tests/schema/tests.py b/tests/schema/tests.py
index 20a00e29f7..80fdead190 100644
--- a/tests/schema/tests.py
+++ b/tests/schema/tests.py
@@ -2257,6 +2257,24 @@ class Meta:
columns = self.column_classes(AuthorDbDefault)
self.assertEqual(columns["renamed_year"][1].default, "1985")
+ @isolate_apps("schema")
+ def test_add_field_both_defaults_preserves_db_default(self):
+ class Author(Model):
+ class Meta:
+ app_label = "schema"
+
+ #self.isolated_local_models = [Author]
+ with connection.schema_editor() as editor:
+ editor.create_model(Author)
+
+ field = IntegerField(default=1985, db_default=1988)
+ field.set_attributes_from_name("birth_year")
+ field.model = Author
+ with connection.schema_editor() as editor:
+ editor.add_field(Author, field)
+ columns = self.column_classes(Author)
+ self.assertEqual(columns["birth_year"][1].default, "1988")
+
@skipUnlessDBFeature(
"supports_column_check_constraints",
"can_introspect_check_constraints"
)
}}}
--
Ticket URL: <https://code.djangoproject.com/ticket/34946>
Django <https://code.djangoproject.com/>
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