Fixed #17061 -- Factored out importing object from a dotted path

Thanks Carl Meyer for the report.

formtools/tests/wizard/loadstorage.py

@@ -1,8 +1,6 @@
 from django.test import TestCase
 
-from django.contrib.formtools.wizard.storage import (get_storage,
-                                                     MissingStorageModule,
-                                                     MissingStorageClass)
+from django.contrib.formtools.wizard.storage import get_storage, MissingStorage
 from django.contrib.formtools.wizard.storage.base import BaseStorage
 
 
@@ -12,11 +10,9 @@ class TestLoadStorage(TestCase):
             type(get_storage('django.contrib.formtools.wizard.storage.base.BaseStorage', 'wizard1')),
             BaseStorage)
 
-    def test_missing_module(self):
-        self.assertRaises(MissingStorageModule, get_storage,
+    def test_missing_storage(self):
+        self.assertRaises(MissingStorage, get_storage,
             'django.contrib.formtools.wizard.storage.idontexist.IDontExistStorage', 'wizard1')
-
-    def test_missing_class(self):
-        self.assertRaises(MissingStorageClass, get_storage,
+        self.assertRaises(MissingStorage, get_storage,
             'django.contrib.formtools.wizard.storage.base.IDontExistStorage', 'wizard1')
 

formtools/wizard/storage/__init__.py

@@ -1,22 +1,14 @@
-from django.utils.importlib import import_module
+from django.core.exceptions import ImproperlyConfigured
+from django.utils.module_loading import import_by_path
 
 from django.contrib.formtools.wizard.storage.base import BaseStorage
 from django.contrib.formtools.wizard.storage.exceptions import (
-    MissingStorageModule, MissingStorageClass, NoFileStorageConfigured)
+    MissingStorage, NoFileStorageConfigured)
 
 
 def get_storage(path, *args, **kwargs):
-    i = path.rfind('.')
-    module, attr = path[:i], path[i+1:]
     try:
-        mod = import_module(module)
-    except ImportError as e:
-        raise MissingStorageModule(
-            'Error loading storage %s: "%s"' % (module, e))
-    try:
-        storage_class = getattr(mod, attr)
-    except AttributeError:
-        raise MissingStorageClass(
-            'Module "%s" does not define a storage named "%s"' % (module, attr))
+        storage_class = import_by_path(path)
+    except ImproperlyConfigured as e:
+        raise MissingStorage('Error loading storage: %s' % e)
     return storage_class(*args, **kwargs)
-

formtools/wizard/storage/exceptions.py

@@ -1,9 +1,6 @@
 from django.core.exceptions import ImproperlyConfigured
 
-class MissingStorageModule(ImproperlyConfigured):
-    pass
-
-class MissingStorageClass(ImproperlyConfigured):
+class MissingStorage(ImproperlyConfigured):
     pass
 
 class NoFileStorageConfigured(ImproperlyConfigured):