From 4d60261b2a77460b4c127c3d832518b95e11a0ac Mon Sep 17 00:00:00 2001
From: Daniel Tao <daniel.tao@gmail.com>
Date: Fri, 15 Sep 2017 16:16:44 -0500
Subject: [PATCH] Fixed #28601 -- Prevented cache.get_or_set() from caching
None if default is a callable that returns None.
---
django/core/cache/backends/base.py | 12 +++++++-----
docs/releases/1.11.7.txt | 3 ++-
tests/cache/tests.py | 5 +++++
3 files changed, 14 insertions(+), 6 deletions(-)
diff --git a/django/core/cache/backends/base.py b/django/core/cache/backends/base.py
index aaf34c042e..cf0df7cc68 100644
--- a/django/core/cache/backends/base.py
+++ b/django/core/cache/backends/base.py
@@ -155,13 +155,15 @@ class BaseCache:
Return the value of the key stored or retrieved.
"""
val = self.get(key, version=version)
- if val is None and default is not None:
+ if val is None:
if callable(default):
default = default()
- self.add(key, default, timeout=timeout, version=version)
- # Fetch the value again to avoid a race condition if another caller
- # added a value between the first get() and the add() above.
- return self.get(key, default, version=version)
+ if default is not None:
+ self.add(key, default, timeout=timeout, version=version)
+ # Fetch the value again to avoid a race condition if another
+ # caller added a value between the first get() and the add()
+ # above.
+ return self.get(key, default, version=version)
return val
def has_key(self, key, version=None):
diff --git a/docs/releases/1.11.7.txt b/docs/releases/1.11.7.txt
index 41d144e742..61f0d6d012 100644
--- a/docs/releases/1.11.7.txt
+++ b/docs/releases/1.11.7.txt
@@ -9,4 +9,5 @@ Django 1.11.7 fixes several bugs in 1.11.6.
Bugfixes
========
-* ...
+* Prevented ``cache.get_or_set()`` from caching ``None`` if the ``default``
+ argument is a callable that returns ``None`` (:ticket:`28601`).
diff --git a/tests/cache/tests.py b/tests/cache/tests.py
index 57e4ec15b4..9a903ef203 100644
--- a/tests/cache/tests.py
+++ b/tests/cache/tests.py
@@ -924,6 +924,11 @@ class BaseCacheTests:
self.assertEqual(cache.get_or_set('mykey', my_callable), 'value')
self.assertEqual(cache.get_or_set('mykey', my_callable()), 'value')
+ def test_get_or_set_callable_returning_none(self):
+ self.assertIsNone(cache.get_or_set('mykey', lambda: None))
+ # Previous get_or_set() doesn't store None in the cache.
+ self.assertEqual(cache.get('mykey', 'default'), 'default')
+
def test_get_or_set_version(self):
msg = "get_or_set() missing 1 required positional argument: 'default'"
cache.get_or_set('brian', 1979, version=2)