Fixed #24865 -- Added remove_stale_contenttypes management command.

Thanks Simon Charette for the review.

8 files changed, 164 insertions, 106 deletions

diff --git a/django/contrib/contenttypes/apps.py b/django/contrib/contenttypes/apps.py
index e5708adc99..5754f8c24c 100644
--- a/django/contrib/contenttypes/apps.py
+++ b/django/contrib/contenttypes/apps.py
@@ -5,7 +5,7 @@ from django.db.models.signals import post_migrate, pre_migrate
 from django.utils.translation import ugettext_lazy as _
 
 from .management import (
-    inject_rename_contenttypes_operations, update_contenttypes,
+    create_contenttypes, inject_rename_contenttypes_operations,
 )
 
 
@@ -15,5 +15,5 @@ class ContentTypesConfig(AppConfig):
 
     def ready(self):
         pre_migrate.connect(inject_rename_contenttypes_operations, sender=self)
-        post_migrate.connect(update_contenttypes)
+        post_migrate.connect(create_contenttypes)
         checks.register(check_generic_foreign_keys, checks.Tags.models)
diff --git a/django/contrib/contenttypes/management.py b/django/contrib/contenttypes/management/__init__.py
index aa1c198fc4..d0d5b52f09 100644
--- a/django/contrib/contenttypes/management.py
+++ b/django/contrib/contenttypes/management/__init__.py
@@ -1,9 +1,7 @@
 from django.apps import apps as global_apps
 from django.db import DEFAULT_DB_ALIAS, migrations, router, transaction
-from django.db.models.deletion import Collector
 from django.db.utils import IntegrityError
 from django.utils import six
-from django.utils.six.moves import input
 
 
 class RenameContentType(migrations.RunPython):
@@ -30,8 +28,8 @@ class RenameContentType(migrations.RunPython):
                     content_type.save(update_fields={'model'})
             except IntegrityError:
                 # Gracefully fallback if a stale content type causes a
-                # conflict as update_contenttypes will take care of asking the
-                # user what should be done next.
+                # conflict as remove_stale_contenttypes will take care of
+                # asking the user what should be done next.
                 content_type.model = old_model
             else:
                 # Clear the cache as the `get_by_natual_key()` call will cache
@@ -87,10 +85,26 @@ def inject_rename_contenttypes_operations(plan=None, apps=global_apps, using=DEF
             migration.operations.insert(inserted + index, operation)
 
 
-def update_contenttypes(app_config, verbosity=2, interactive=True, using=DEFAULT_DB_ALIAS, apps=global_apps, **kwargs):
+def get_contenttypes_and_models(app_config, using, ContentType):
+    if not router.allow_migrate_model(using, ContentType):
+        return None, None
+
+    ContentType.objects.clear_cache()
+
+    content_types = {
+        ct.model: ct
+        for ct in ContentType.objects.using(using).filter(app_label=app_config.label)
+    }
+    app_models = {
+        model._meta.model_name: model
+        for model in app_config.get_models()
+    }
+    return content_types, app_models
+
+
+def create_contenttypes(app_config, verbosity=2, interactive=True, using=DEFAULT_DB_ALIAS, apps=global_apps, **kwargs):
     """
-    Creates content types for models in the given app, removing any model
-    entries that no longer have a matching model class.
+    Creates content types for models in the given app.
     """
     if not app_config.models_module:
         return
@@ -102,32 +116,11 @@ def update_contenttypes(app_config, verbosity=2, interactive=True, using=DEFAULT
     except LookupError:
         return
 
-    if not router.allow_migrate_model(using, ContentType):
-        return
-
-    ContentType.objects.clear_cache()
-    # Always clear the global content types cache.
-    if apps is not global_apps:
-        global_apps.get_model('contenttypes', 'ContentType').objects.clear_cache()
-
-    app_models = {
-        model._meta.model_name: model
-        for model in app_config.get_models()}
+    content_types, app_models = get_contenttypes_and_models(app_config, using, ContentType)
 
     if not app_models:
         return
 
-    # Get all the content types
-    content_types = {
-        ct.model: ct
-        for ct in ContentType.objects.using(using).filter(app_label=app_label)
-    }
-    to_remove = [
-        ct
-        for (model_name, ct) in six.iteritems(content_types)
-        if model_name not in app_models
-    ]
-
     cts = [
         ContentType(
             app_label=app_label,
@@ -140,55 +133,3 @@ def update_contenttypes(app_config, verbosity=2, interactive=True, using=DEFAULT
     if verbosity >= 2:
         for ct in cts:
             print("Adding content type '%s | %s'" % (ct.app_label, ct.model))
-
-    # Confirm that the content type is stale before deletion.
-    using = router.db_for_write(ContentType)
-    if to_remove:
-        if interactive:
-            ct_info = []
-            for ct in to_remove:
-                ct_info.append('    - Content type for %s.%s' % (ct.app_label, ct.model))
-                collector = NoFastDeleteCollector(using=using)
-                collector.collect([ct])
-
-                for obj_type, objs in collector.data.items():
-                    if objs == {ct}:
-                        continue
-                    ct_info.append('    - %s %s object(s)' % (
-                        len(objs),
-                        obj_type._meta.label,
-                    ))
-
-            content_type_display = '\n'.join(ct_info)
-            print("""Some content types in your database are stale and can be deleted.
-Any objects that depend on these content types will also be deleted.
-The content types and dependent objects that would be deleted are:
-
-%s
-
-This list doesn't include any cascade deletions to data outside of Django's
-models (uncommon).
-
-Are you sure you want to delete these content types?
-If you're unsure, answer 'no'.
-    """ % content_type_display)
-            ok_to_delete = input("Type 'yes' to continue, or 'no' to cancel: ")
-        else:
-            ok_to_delete = False
-
-        if ok_to_delete == 'yes':
-            for ct in to_remove:
-                if verbosity >= 2:
-                    print("Deleting stale content type '%s | %s'" % (ct.app_label, ct.model))
-                ct.delete()
-        else:
-            if verbosity >= 2:
-                print("Stale content types remain.")
-
-
-class NoFastDeleteCollector(Collector):
-    def can_fast_delete(self, *args, **kwargs):
-        """
-        Always load related objects to display them when showing confirmation.
-        """
-        return False
diff --git a/django/contrib/contenttypes/management/commands/__init__.py b/django/contrib/contenttypes/management/commands/__init__.py
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/django/contrib/contenttypes/management/commands/__init__.py
diff --git a/django/contrib/contenttypes/management/commands/remove_stale_contenttypes.py b/django/contrib/contenttypes/management/commands/remove_stale_contenttypes.py
new file mode 100644
index 0000000000..2a3b23b0d0
--- /dev/null
+++ b/django/contrib/contenttypes/management/commands/remove_stale_contenttypes.py
@@ -0,0 +1,86 @@
+from django.apps import apps
+from django.contrib.contenttypes.models import ContentType
+from django.core.management import BaseCommand
+from django.db import DEFAULT_DB_ALIAS, router
+from django.db.models.deletion import Collector
+from django.utils import six
+from django.utils.six.moves import input
+
+from ...management import get_contenttypes_and_models
+
+
+class Command(BaseCommand):
+
+    def add_arguments(self, parser):
+        parser.add_argument(
+            '--noinput', '--no-input',
+            action='store_false', dest='interactive', default=True,
+            help='Tells Django to NOT prompt the user for input of any kind.',
+        )
+        parser.add_argument(
+            '--database', action='store', dest='database', default=DEFAULT_DB_ALIAS,
+            help='Nominates the database to use. Defaults to the "default" database.',
+        )
+
+    def handle(self, **options):
+        db = options['database']
+        interactive = options['interactive']
+        verbosity = options['verbosity']
+
+        for app_config in apps.get_app_configs():
+            content_types, app_models = get_contenttypes_and_models(app_config, db, ContentType)
+            if not app_models:
+                continue
+            to_remove = [
+                ct for (model_name, ct) in six.iteritems(content_types)
+                if model_name not in app_models
+            ]
+            # Confirm that the content type is stale before deletion.
+            using = router.db_for_write(ContentType)
+            if to_remove:
+                if interactive:
+                    ct_info = []
+                    for ct in to_remove:
+                        ct_info.append('    - Content type for %s.%s' % (ct.app_label, ct.model))
+                        collector = NoFastDeleteCollector(using=using)
+                        collector.collect([ct])
+
+                        for obj_type, objs in collector.data.items():
+                            if objs == {ct}:
+                                continue
+                            ct_info.append('    - %s %s object(s)' % (
+                                len(objs),
+                                obj_type._meta.label,
+                            ))
+                        content_type_display = '\n'.join(ct_info)
+                    self.stdout.write("""Some content types in your database are stale and can be deleted.
+Any objects that depend on these content types will also be deleted.
+The content types and dependent objects that would be deleted are:
+
+%s
+
+This list doesn't include any cascade deletions to data outside of Django's
+models (uncommon).
+
+Are you sure you want to delete these content types?
+If you're unsure, answer 'no'.\n""" % content_type_display)
+                    ok_to_delete = input("Type 'yes' to continue, or 'no' to cancel: ")
+                else:
+                    ok_to_delete = False
+
+                if ok_to_delete == 'yes':
+                    for ct in to_remove:
+                        if verbosity >= 2:
+                            self.stdout.write("Deleting stale content type '%s | %s'" % (ct.app_label, ct.model))
+                        ct.delete()
+                else:
+                    if verbosity >= 2:
+                        self.stdout.write("Stale content types remain.")
+
+
+class NoFastDeleteCollector(Collector):
+    def can_fast_delete(self, *args, **kwargs):
+        """
+        Always load related objects to display them when showing confirmation.
+        """
+        return False
diff --git a/django/contrib/contenttypes/models.py b/django/contrib/contenttypes/models.py
index 21432f897a..4823e2251a 100644
--- a/django/contrib/contenttypes/models.py
+++ b/django/contrib/contenttypes/models.py
@@ -118,10 +118,7 @@ class ContentTypeManager(models.Manager):
 
     def clear_cache(self):
         """
-        Clear out the content-type cache. This needs to happen during database
-        flushes to prevent caching of "stale" content type IDs (see
-        django.contrib.contenttypes.management.update_contenttypes for where
-        this gets called).
+        Clear out the content-type cache.
         """
         self._cache.clear()
 
diff --git a/docs/ref/django-admin.txt b/docs/ref/django-admin.txt
index 3421478f33..74f105be74 100644
--- a/docs/ref/django-admin.txt
+++ b/docs/ref/django-admin.txt
@@ -1456,6 +1456,28 @@ it could be useful if you have a ``ForeignKey`` in
 allow creating an instance instead of entering the primary key of an existing
 instance.
 
+``django.contrib.contenttypes``
+-------------------------------
+
+``remove_stale_contenttypes``
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+.. django-admin:: remove_stale_contenttypes
+
+.. versionadded:: 1.11
+
+This command is only available if Django's :doc:`contenttypes app
+</ref/contrib/contenttypes>` (:mod:`django.contrib.contenttypes`) is installed.
+
+Deletes stale content types (from deleted models) in your database. Any objects
+that depend on the deleted content types will also be deleted. A list of
+deleted objects will be displayed before you confirm it's okay to proceed with
+the deletion.
+
+.. django-admin-option:: --database DATABASE
+
+Specifies the database to use. Defaults to ``default``.
+
 ``django.contrib.gis``
 ----------------------
 
diff --git a/docs/releases/1.11.txt b/docs/releases/1.11.txt
index bb8c851f72..46bc7f1529 100644
--- a/docs/releases/1.11.txt
+++ b/docs/releases/1.11.txt
@@ -104,9 +104,11 @@ Minor features
 :mod:`django.contrib.contenttypes`
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
-* When stale content types are detected after the ``migrate`` command, there's
-  now a list of related objects such as ``auth.Permission``\s that will also be
-  deleted. Previously, only the content types were listed.
+* When stale content types are detected in the
+  :djadmin:`remove_stale_contenttypes` command, there's now a list of related
+  objects such as ``auth.Permission``\s that will also be deleted. Previously,
+  only the content types were listed (and this prompt was after ``migrate``
+  rather than in a separate command).
 
 :mod:`django.contrib.gis`
 ~~~~~~~~~~~~~~~~~~~~~~~~~
@@ -477,6 +479,10 @@ Miscellaneous
   be backwards-incompatible if you have some :ref:`template tags that aren't
   thread safe <template_tag_thread_safety>`.
 
+* The prompt for stale content type deletion no longer occurs after running the
+  ``migrate`` command. Use the new :djadmin:`remove_stale_contenttypes` command
+  instead.
+
 .. _deprecated-features-1.11:
 
 Features deprecated in 1.11
diff --git a/tests/contenttypes_tests/tests.py b/tests/contenttypes_tests/tests.py
index 6d57a23355..ef13d3f4bb 100644
--- a/tests/contenttypes_tests/tests.py
+++ b/tests/contenttypes_tests/tests.py
@@ -12,6 +12,7 @@ from django.contrib.contenttypes.fields import (
 from django.contrib.contenttypes.models import ContentType
 from django.contrib.sites.models import Site
 from django.core import checks, management
+from django.core.management import call_command
 from django.db import connections, migrations, models
 from django.test import (
     SimpleTestCase, TestCase, TransactionTestCase, mock, override_settings,
@@ -388,16 +389,19 @@ class UpdateContentTypesTests(TestCase):
 
     def test_interactive_true_with_dependent_objects(self):
         """
-        interactive mode of update_contenttypes() (the default) should delete
-        stale contenttypes and warn of dependent objects.
+        interactive mode of remove_stale_contenttypes (the default) should
+        delete stale contenttypes and warn of dependent objects.
         """
         post = Post.objects.create(title='post', content_type=self.content_type)
         # A related object is needed to show that a custom collector with
         # can_fast_delete=False is needed.
         ModelWithNullFKToSite.objects.create(post=post)
-        contenttypes_management.input = lambda x: force_str("yes")
-        with captured_stdout() as stdout:
-            contenttypes_management.update_contenttypes(self.app_config)
+        with mock.patch(
+            'django.contrib.contenttypes.management.commands.remove_stale_contenttypes.input',
+            return_value='yes'
+        ):
+            with captured_stdout() as stdout:
+                call_command('remove_stale_contenttypes', verbosity=2, stdout=stdout)
         self.assertEqual(Post.objects.count(), 0)
         output = stdout.getvalue()
         self.assertIn('- Content type for contenttypes_tests.Fake', output)
@@ -408,33 +412,35 @@ class UpdateContentTypesTests(TestCase):
 
     def test_interactive_true_without_dependent_objects(self):
         """
-        interactive mode of update_contenttypes() (the default) should delete
-        stale contenttypes even if there aren't any dependent objects.
+        interactive mode of remove_stale_contenttypes (the default) should
+        delete stale contenttypes even if there aren't any dependent objects.
         """
-        contenttypes_management.input = lambda x: force_str("yes")
-        with captured_stdout() as stdout:
-            contenttypes_management.update_contenttypes(self.app_config)
+        with mock.patch(
+            'django.contrib.contenttypes.management.commands.remove_stale_contenttypes.input',
+            return_value='yes'
+        ):
+            with captured_stdout() as stdout:
+                call_command('remove_stale_contenttypes', verbosity=2)
         self.assertIn("Deleting stale content type", stdout.getvalue())
         self.assertEqual(ContentType.objects.count(), self.before_count)
 
     def test_interactive_false(self):
         """
-        non-interactive mode of update_contenttypes() shouldn't delete stale
-        content types.
+        non-interactive mode of remove_stale_contenttypes shouldn't delete
+        stale content types.
         """
         with captured_stdout() as stdout:
-            contenttypes_management.update_contenttypes(self.app_config, interactive=False)
+            call_command('remove_stale_contenttypes', interactive=False, verbosity=2)
         self.assertIn("Stale content types remain.", stdout.getvalue())
         self.assertEqual(ContentType.objects.count(), self.before_count + 1)
 
     def test_unavailable_content_type_model(self):
         """
-        #24075 - A ContentType shouldn't be created or deleted if the model
-        isn't available.
+        A ContentType shouldn't be created if the model isn't available.
         """
         apps = Apps()
         with self.assertNumQueries(0):
-            contenttypes_management.update_contenttypes(self.app_config, interactive=False, verbosity=0, apps=apps)
+            contenttypes_management.create_contenttypes(self.app_config, interactive=False, verbosity=0, apps=apps)
         self.assertEqual(ContentType.objects.count(), self.before_count + 1)