Fixed #31007 -- Allowed specifying type of auto-created primary keys.

This also changes the default type of auto-created primary keys
for new apps and projects to BigAutoField.

8 files changed, 241 insertions, 2 deletions

diff --git a/tests/admin_scripts/tests.py b/tests/admin_scripts/tests.py
index a82f5be5ed..7a38306d17 100644
--- a/tests/admin_scripts/tests.py
+++ b/tests/admin_scripts/tests.py
@@ -61,6 +61,7 @@ class AdminScriptTestCase(SimpleTestCase):
                 settings_file.write("%s\n" % extra)
             exports = [
                 'DATABASES',
+                'DEFAULT_AUTO_FIELD',
                 'ROOT_URLCONF',
                 'SECRET_KEY',
             ]
@@ -2188,6 +2189,20 @@ class StartApp(AdminScriptTestCase):
             "won't replace conflicting files."
         )
 
+    def test_template(self):
+        out, err = self.run_django_admin(['startapp', 'new_app'])
+        self.assertNoOutput(err)
+        app_path = os.path.join(self.test_dir, 'new_app')
+        self.assertIs(os.path.exists(app_path), True)
+        with open(os.path.join(app_path, 'apps.py')) as f:
+            content = f.read()
+            self.assertIn('class NewAppConfig(AppConfig)', content)
+            self.assertIn(
+                "default_auto_field = 'django.db.models.BigAutoField'",
+                content,
+            )
+            self.assertIn("name = 'new_app'", content)
+
 
 class DiffSettings(AdminScriptTestCase):
     """Tests for diffsettings management command."""
diff --git a/tests/apps/apps.py b/tests/apps/apps.py
index d322b28f2b..efd2983779 100644
--- a/tests/apps/apps.py
+++ b/tests/apps/apps.py
@@ -31,3 +31,8 @@ class PlainAppsConfig(AppConfig):
 class RelabeledAppsConfig(AppConfig):
     name = 'apps'
     label = 'relabeled'
+
+
+class ModelPKAppsConfig(AppConfig):
+    name = 'apps'
+    default_auto_field = 'django.db.models.BigAutoField'
diff --git a/tests/apps/tests.py b/tests/apps/tests.py
index 26d135f244..0e1f918bcc 100644
--- a/tests/apps/tests.py
+++ b/tests/apps/tests.py
@@ -102,8 +102,8 @@ class AppsTests(SimpleTestCase):
     def test_no_such_app_config_with_choices(self):
         msg = (
             "Module 'apps.apps' does not contain a 'NoSuchConfig' class. "
-            "Choices are: 'BadConfig', 'MyAdmin', 'MyAuth', 'NoSuchApp', "
-            "'PlainAppsConfig', 'RelabeledAppsConfig'."
+            "Choices are: 'BadConfig', 'ModelPKAppsConfig', 'MyAdmin', "
+            "'MyAuth', 'NoSuchApp', 'PlainAppsConfig', 'RelabeledAppsConfig'."
         )
         with self.assertRaisesMessage(ImportError, msg):
             with self.settings(INSTALLED_APPS=['apps.apps.NoSuchConfig']):
@@ -436,6 +436,30 @@ class AppConfigTests(SimpleTestCase):
         ac = AppConfig('label', Stub(__path__=['a']))
         self.assertEqual(repr(ac), '<AppConfig: label>')
 
+    @override_settings(
+        INSTALLED_APPS=['apps.apps.ModelPKAppsConfig'],
+        DEFAULT_AUTO_FIELD='django.db.models.SmallAutoField',
+    )
+    def test_app_default_auto_field(self):
+        apps_config = apps.get_app_config('apps')
+        self.assertEqual(
+            apps_config.default_auto_field,
+            'django.db.models.BigAutoField',
+        )
+        self.assertIs(apps_config._is_default_auto_field_overridden, True)
+
+    @override_settings(
+        INSTALLED_APPS=['apps.apps.PlainAppsConfig'],
+        DEFAULT_AUTO_FIELD='django.db.models.SmallAutoField',
+    )
+    def test_default_auto_field_setting(self):
+        apps_config = apps.get_app_config('apps')
+        self.assertEqual(
+            apps_config.default_auto_field,
+            'django.db.models.SmallAutoField',
+        )
+        self.assertIs(apps_config._is_default_auto_field_overridden, False)
+
 
 class NamespacePackageAppTests(SimpleTestCase):
     # We need nsapp to be top-level so our multiple-paths tests can add another
diff --git a/tests/check_framework/apps.py b/tests/check_framework/apps.py
new file mode 100644
index 0000000000..c57994f722
--- /dev/null
+++ b/tests/check_framework/apps.py
@@ -0,0 +1,10 @@
+from django.apps import AppConfig
+
+
+class CheckDefaultPKConfig(AppConfig):
+    name = 'check_framework'
+
+
+class CheckPKConfig(AppConfig):
+    name = 'check_framework'
+    default_auto_field = 'django.db.models.BigAutoField'
diff --git a/tests/check_framework/test_model_checks.py b/tests/check_framework/test_model_checks.py
index ce2d73fa20..d4342ada07 100644
--- a/tests/check_framework/test_model_checks.py
+++ b/tests/check_framework/test_model_checks.py
@@ -1,3 +1,5 @@
+from unittest import mock
+
 from django.core import checks
 from django.core.checks import Error, Warning
 from django.db import models
@@ -358,3 +360,58 @@ class ConstraintNameTests(TestCase):
                 constraints = [constraint]
 
         self.assertEqual(checks.run_checks(app_configs=apps.get_app_configs()), [])
+
+
+def mocked_is_overridden(self, setting):
+    # Force treating DEFAULT_AUTO_FIELD = 'django.db.models.AutoField' as a not
+    # overridden setting.
+    return (
+        setting != 'DEFAULT_AUTO_FIELD' or
+        self.DEFAULT_AUTO_FIELD != 'django.db.models.AutoField'
+    )
+
+
+@mock.patch('django.conf.UserSettingsHolder.is_overridden', mocked_is_overridden)
+@override_settings(DEFAULT_AUTO_FIELD='django.db.models.AutoField')
+@isolate_apps('check_framework.apps.CheckDefaultPKConfig', attr_name='apps')
+@override_system_checks([checks.model_checks.check_all_models])
+class ModelDefaultAutoFieldTests(SimpleTestCase):
+    def test_auto_created_pk(self):
+        class Model(models.Model):
+            pass
+
+        self.assertEqual(checks.run_checks(app_configs=self.apps.get_app_configs()), [
+            Warning(
+                "Auto-created primary key used when not defining a primary "
+                "key type, by default 'django.db.models.AutoField'.",
+                hint=(
+                    "Configure the DEFAULT_AUTO_FIELD setting or the "
+                    "CheckDefaultPKConfig.default_auto_field attribute to "
+                    "point to a subclass of AutoField, e.g. "
+                    "'django.db.models.BigAutoField'."
+                ),
+                obj=Model,
+                id='models.W042',
+            ),
+        ])
+
+    @override_settings(DEFAULT_AUTO_FIELD='django.db.models.BigAutoField')
+    def test_default_auto_field_setting(self):
+        class Model(models.Model):
+            pass
+
+        self.assertEqual(checks.run_checks(app_configs=self.apps.get_app_configs()), [])
+
+    def test_explicit_pk(self):
+        class Model(models.Model):
+            id = models.BigAutoField(primary_key=True)
+
+        self.assertEqual(checks.run_checks(app_configs=self.apps.get_app_configs()), [])
+
+    @isolate_apps('check_framework.apps.CheckPKConfig', kwarg_name='apps')
+    def test_app_default_auto_field(self, apps):
+        class ModelWithPkViaAppConfig(models.Model):
+            class Meta:
+                app_label = 'check_framework.apps.CheckPKConfig'
+
+        self.assertEqual(checks.run_checks(app_configs=apps.get_app_configs()), [])
diff --git a/tests/model_options/apps.py b/tests/model_options/apps.py
new file mode 100644
index 0000000000..be2250fe7a
--- /dev/null
+++ b/tests/model_options/apps.py
@@ -0,0 +1,25 @@
+from django.apps import AppConfig
+
+
+class ModelDefaultPKConfig(AppConfig):
+    name = 'model_options'
+
+
+class ModelPKConfig(AppConfig):
+    name = 'model_options'
+    default_auto_field = 'django.db.models.SmallAutoField'
+
+
+class ModelPKNonAutoConfig(AppConfig):
+    name = 'model_options'
+    default_auto_field = 'django.db.models.TextField'
+
+
+class ModelPKNoneConfig(AppConfig):
+    name = 'model_options'
+    default_auto_field = None
+
+
+class ModelPKNonexistentConfig(AppConfig):
+    name = 'model_options'
+    default_auto_field = 'django.db.models.NonexistentAutoField'
diff --git a/tests/model_options/test_default_pk.py b/tests/model_options/test_default_pk.py
new file mode 100644
index 0000000000..b678848916
--- /dev/null
+++ b/tests/model_options/test_default_pk.py
@@ -0,0 +1,101 @@
+from django.core.exceptions import ImproperlyConfigured
+from django.db import models
+from django.test import SimpleTestCase, override_settings
+from django.test.utils import isolate_apps
+
+
+@isolate_apps('model_options')
+class TestDefaultPK(SimpleTestCase):
+    @override_settings(DEFAULT_AUTO_FIELD='django.db.models.NonexistentAutoField')
+    def test_default_auto_field_setting_nonexistent(self):
+        msg = (
+            "DEFAULT_AUTO_FIELD refers to the module "
+            "'django.db.models.NonexistentAutoField' that could not be "
+            "imported."
+        )
+        with self.assertRaisesMessage(ImproperlyConfigured, msg):
+            class Model(models.Model):
+                pass
+
+    @isolate_apps('model_options.apps.ModelPKNonexistentConfig')
+    def test_app_default_auto_field_nonexistent(self):
+        msg = (
+            "model_options.apps.ModelPKNonexistentConfig.default_auto_field "
+            "refers to the module 'django.db.models.NonexistentAutoField' "
+            "that could not be imported."
+        )
+        with self.assertRaisesMessage(ImproperlyConfigured, msg):
+            class Model(models.Model):
+                pass
+
+    @override_settings(DEFAULT_AUTO_FIELD='django.db.models.TextField')
+    def test_default_auto_field_setting_non_auto(self):
+        msg = (
+            "Primary key 'django.db.models.TextField' referred by "
+            "DEFAULT_AUTO_FIELD must subclass AutoField."
+        )
+        with self.assertRaisesMessage(ValueError, msg):
+            class Model(models.Model):
+                pass
+
+    @isolate_apps('model_options.apps.ModelPKNonAutoConfig')
+    def test_app_default_auto_field_non_auto(self):
+        msg = (
+            "Primary key 'django.db.models.TextField' referred by "
+            "model_options.apps.ModelPKNonAutoConfig.default_auto_field must "
+            "subclass AutoField."
+        )
+        with self.assertRaisesMessage(ValueError, msg):
+            class Model(models.Model):
+                pass
+
+    @override_settings(DEFAULT_AUTO_FIELD=None)
+    def test_default_auto_field_setting_none(self):
+        msg = 'DEFAULT_AUTO_FIELD must not be empty.'
+        with self.assertRaisesMessage(ImproperlyConfigured, msg):
+            class Model(models.Model):
+                pass
+
+    @isolate_apps('model_options.apps.ModelPKNoneConfig')
+    def test_app_default_auto_field_none(self):
+        msg = (
+            'model_options.apps.ModelPKNoneConfig.default_auto_field must not '
+            'be empty.'
+        )
+        with self.assertRaisesMessage(ImproperlyConfigured, msg):
+            class Model(models.Model):
+                pass
+
+    @isolate_apps('model_options.apps.ModelDefaultPKConfig')
+    @override_settings(DEFAULT_AUTO_FIELD='django.db.models.SmallAutoField')
+    def test_default_auto_field_setting(self):
+        class Model(models.Model):
+            pass
+
+        self.assertIsInstance(Model._meta.pk, models.SmallAutoField)
+
+    @isolate_apps('model_options.apps.ModelPKConfig')
+    @override_settings(DEFAULT_AUTO_FIELD='django.db.models.AutoField')
+    def test_app_default_auto_field(self):
+        class Model(models.Model):
+            pass
+
+        self.assertIsInstance(Model._meta.pk, models.SmallAutoField)
+
+    @isolate_apps('model_options.apps.ModelDefaultPKConfig')
+    @override_settings(DEFAULT_AUTO_FIELD='django.db.models.SmallAutoField')
+    def test_m2m_default_auto_field_setting(self):
+        class M2MModel(models.Model):
+            m2m = models.ManyToManyField('self')
+
+        m2m_pk = M2MModel._meta.get_field('m2m').remote_field.through._meta.pk
+        self.assertIsInstance(m2m_pk, models.SmallAutoField)
+
+    @isolate_apps('model_options.apps.ModelPKConfig')
+    @override_settings(DEFAULT_AUTO_FIELD='django.db.models.AutoField')
+    def test_m2m_app_default_auto_field(self):
+        class M2MModel(models.Model):
+            m2m = models.ManyToManyField('self')
+
+        m2m_pk = M2MModel._meta.get_field('m2m').remote_field.through._meta.pk
+        self.assertIsInstance(m2m_pk, models.SmallAutoField)
diff --git a/tests/test_sqlite.py b/tests/test_sqlite.py
index f1b65f7d01..099f37e56d 100644
--- a/tests/test_sqlite.py
+++ b/tests/test_sqlite.py
@@ -27,3 +27,5 @@ SECRET_KEY = "django_tests_secret_key"
 PASSWORD_HASHERS = [
     'django.contrib.auth.hashers.MD5PasswordHasher',
 ]
+
+DEFAULT_AUTO_FIELD = 'django.db.models.AutoField'