Fixed #21042 -- Allowed accessing FileDescriptor on the model class.

This is consistent with ability to reference other descriptors
on the model class (5ef0c03ae9aca99289737ba6d88a371ad95cf432).

2 files changed, 3 insertions, 6 deletions

diff --git a/django/db/models/fields/files.py b/django/db/models/fields/files.py
index 184a8dbd69..c4c44f18f8 100644
--- a/django/db/models/fields/files.py
+++ b/django/db/models/fields/files.py
@@ -157,9 +157,7 @@ class FileDescriptor(object):
 
     def __get__(self, instance=None, owner=None):
         if instance is None:
-            raise AttributeError(
-                "The '%s' attribute can only be accessed from %s instances."
-                % (self.field.name, owner.__name__))
+            return self
 
         # This is slightly complicated, so worth an explanation.
         # instance.file`needs to ultimately return some instance of `File`,
diff --git a/tests/file_storage/tests.py b/tests/file_storage/tests.py
index 8ff3959427..6b02073bbf 100644
--- a/tests/file_storage/tests.py
+++ b/tests/file_storage/tests.py
@@ -18,6 +18,7 @@ from django.core.files.storage import FileSystemStorage, get_storage_class
 from django.core.files.uploadedfile import (
     InMemoryUploadedFile, SimpleUploadedFile, TemporaryUploadedFile,
 )
+from django.db.models.fields.files import FileDescriptor
 from django.test import (
     LiveServerTestCase, SimpleTestCase, TestCase, override_settings,
 )
@@ -447,9 +448,7 @@ class FileFieldStorageTests(TestCase):
             return 255  # Should be safe on most backends
 
     def test_files(self):
-        # Attempting to access a FileField from the class raises a descriptive
-        # error
-        self.assertRaises(AttributeError, lambda: Storage.normal)
+        self.assertIsInstance(Storage.normal, FileDescriptor)
 
         # An object without a file has limited functionality.
         obj1 = Storage()