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Added a return value to the add() method for caches. It's now possibl…

…e to tell

if a call to add() ended up storing something in the cache.


git-svn-id: http://code.djangoproject.com/svn/django/trunk@8278 bcc190cf-cafb-0310-a4f2-bffc1f526a37
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commit f6670e1341c6b01c5b24b9274aac05d026e536c5 1 parent 38dc472
@malcolmt malcolmt authored
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2  django/core/cache/backends/base.py
@@ -19,6 +19,8 @@ def add(self, key, value, timeout=None):
Set a value in the cache if the key does not already exist. If
timeout is given, that timeout will be used for the key; otherwise
the default cache timeout will be used.
+
+ Returns True if the value was stored, False otherwise.
"""
raise NotImplementedError
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5 django/core/cache/backends/db.py
@@ -38,7 +38,7 @@ def get(self, key, default=None):
return pickle.loads(base64.decodestring(row[1]))
def set(self, key, value, timeout=None):
- return self._base_set('set', key, value, timeout)
+ self._base_set('set', key, value, timeout)
def add(self, key, value, timeout=None):
return self._base_set('add', key, value, timeout)
@@ -62,9 +62,10 @@ def _base_set(self, mode, key, value, timeout=None):
cursor.execute("INSERT INTO %s (cache_key, value, expires) VALUES (%%s, %%s, %%s)" % self._table, [key, encoded, str(exp)])
except DatabaseError:
# To be threadsafe, updates/inserts are allowed to fail silently
- pass
+ return False
else:
transaction.commit_unless_managed()
+ return True
def delete(self, key):
cursor = connection.cursor()
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2  django/core/cache/backends/dummy.py
@@ -7,7 +7,7 @@ def __init__(self, *args, **kwargs):
pass
def add(self, *args, **kwargs):
- pass
+ return True
def get(self, key, default=None):
return default
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3  django/core/cache/backends/filebased.py
@@ -32,9 +32,10 @@ def __init__(self, dir, params):
def add(self, key, value, timeout=None):
if self.has_key(key):
- return None
+ return False
self.set(key, value, timeout)
+ return True
def get(self, key, default=None):
fname = self._key_to_file(key)
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2  django/core/cache/backends/locmem.py
@@ -36,8 +36,10 @@ def add(self, key, value, timeout=None):
if exp is None or exp <= time.time():
try:
self._set(key, pickle.dumps(value), timeout)
+ return True
except pickle.PickleError:
pass
+ return False
finally:
self._lock.writer_leaves()
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2  django/core/cache/backends/memcached.py
@@ -17,7 +17,7 @@ def __init__(self, server, params):
self._cache = memcache.Client(server.split(';'))
def add(self, key, value, timeout=0):
- self._cache.add(key.encode('ascii', 'ignore'), value, timeout or self.default_timeout)
+ return self._cache.add(key.encode('ascii', 'ignore'), value, timeout or self.default_timeout)
def get(self, key, default=None):
val = self._cache.get(smart_str(key))
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10 docs/cache.txt
@@ -410,9 +410,13 @@ it will not attempt to update the cache if the key specified is already present:
>>> cache.get('add_key')
'Initial value'
-There's also a ``get_many()`` interface that only hits the cache once. ``get_many()``
-returns a dictionary with all the keys you asked for that actually exist in the
-cache (and haven't expired)::
+If you need to know whether ``add()`` stored a value in the cache, you can
+check the return value. It will return ``True`` if the value was stored,
+``False`` otherwise.
+
+There's also a ``get_many()`` interface that only hits the cache once.
+``get_many()`` returns a dictionary with all the keys you asked for that
+actually exist in the cache (and haven't expired)::
>>> cache.set('a', 1)
>>> cache.set('b', 2)
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3  tests/regressiontests/cache/tests.py
@@ -31,7 +31,8 @@ def test_simple(self):
def test_add(self):
# test add (only add if key isn't already in cache)
cache.add("addkey1", "value")
- cache.add("addkey1", "newvalue")
+ result = cache.add("addkey1", "newvalue")
+ self.assertEqual(result, False)
self.assertEqual(cache.get("addkey1"), "value")
def test_non_existent(self):
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