Fixed #25547 -- Made Model.refresh_from_db() update FileField's instance.

django/db/models/fields/files.py

@@ -202,6 +202,10 @@ class FileDescriptor(object):
             file.field = self.field
             file.storage = self.field.storage
 
+        # Make sure that the instance is correct.
+        elif isinstance(file, FieldFile) and instance is not file.instance:
+            file.instance = instance
+
         # That was fun, wasn't it?
         return instance.__dict__[self.field.name]
 

tests/model_fields/tests.py

@@ -792,6 +792,11 @@ class FileFieldTests(unittest.TestCase):
         except OSError:
             self.fail("Deleting an unset FileField should not raise OSError.")
 
+    def test_refresh_from_db(self):
+        d = Document.objects.create(myfile='something.txt')
+        d.refresh_from_db()
+        self.assertIs(d.myfile.instance, d)
+
 
 class BinaryFieldTests(test.TestCase):
     binary_data = b'\x00\x46\xFE'