使用django自帶的模組處理redis快取時(shí)，設(shè)定好的key比如說時(shí)“banners”， 到了在redis的cli下看到name就變成了“:1:banners”，這是django的機(jī)制，還是redis的呢
from django.core.cache import cache
def get_queryset(self):
key = "banners"
queryset = cache.get(key)
if not queryset:
queryset = Banner.objects.filter(valid=True)
cache.set(key, queryset, 3600)
return queryset
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你自己在設(shè)定redis會(huì)選擇redis的函式庫，redis本身就分成幾個(gè)函式庫，看你設(shè)定是哪一個(gè)
這個(gè)是django cache的機(jī)制, key由前綴，版本號(hào)，真正的key組成。 django在升級(jí)或程式碼重構(gòu)的時(shí)候有用，可以判斷key是那個(gè)版本號(hào)，從而進(jìn)行相容（其它歡迎補(bǔ)充）
1.首先看django redis client api的實(shí)作:
# https://github.com/niwinz/django-redis/blob/master/django_redis/client/default.py
def get(self, key, default=None, version=None, client=None):
"""
Retrieve a value from the cache.
Returns decoded value if key is found, the default if not.
"""
if client is None:
client = self.get_client(write=False)
key = self.make_key(key, version=version)
try:
value = client.get(key)
except _main_exceptions as e:
raise ConnectionInterrupted(connection=client, parent=e)
if value is None:
return default
return self.decode(value)
... 中間省略代碼 ...
def make_key(self, key, version=None, prefix=None):
if isinstance(key, CacheKey):
return key
if prefix is None:
prefix = self._backend.key_prefix
if version is None:
version = self._backend.version
return CacheKey(self._backend.key_func(key, prefix, version))
它使用了make_key這個(gè)函數(shù)製作新的key,至於真正的key是從_backend.key_func來的。
2.其次查看django cache backend實(shí)作
# https://github.com/django/django/blob/master/django/core/cache/backends/base.py
def default_key_func(key, key_prefix, version):
"""
Default function to generate keys.
Constructs the key used by all other methods. By default it prepends
the `key_prefix'. KEY_FUNCTION can be used to specify an alternate
function with custom key making behavior.
"""
return '%s:%s:%s' % (key_prefix, version, key)
def get_key_func(key_func):
"""
Function to decide which key function to use.
Defaults to ``default_key_func``.
"""
if key_func is not None:
if callable(key_func):
return key_func
else:
return import_string(key_func)
return default_key_func
class BaseCache(object):
def __init__(self, params):
... 中間省略代碼 ...
self.key_prefix = params.get('KEY_PREFIX', '')
self.version = params.get('VERSION', 1)
self.key_func = get_key_func(params.get('KEY_FUNCTION'))
由此可見，django redis cache的key是有前綴，版本號(hào)，真正的key組成。
