[英]Django-redis-cache failing to fetch data from redis
我對這個程序包的工作有疑問。 它如何寫入redis db?
這是我對Redis的設置-
CACHES = {
'default': {
'BACKEND': 'redis_cache.RedisCache',
'LOCATION': '/var/run/redis/redis.sock',
'OPTIONS': {
'DB': 2,
},
},
}
這是我的意見檔案,
def postview(request):
print("Working")
#post_list = Post.objects.all()
if cache.get("posts") == None:
post_list = Post.objects.all()
print("going to be cached")
a = cache.get("aman")
print("aman ", a)
cache.set("posts", post_list, timeout=60*100*10)
print("cached")
else :
post_list = cache.get("posts")
aman = cache.get("aman")
print(aman, " aman's job")
print("already present in cache")
context = {"post_list" : post_list}
print("Problem")
return render(request, 'post_list.html', context)
@cache_page(60*15*10, key_prefix="cache_redis")
def testview(request):
post_list = cache.get("posts")
print("post_list is", post_list)
return render(request, 'post_list.html', {"post_list":post_list})
@cache_page(60*25*10, key_prefix="cache_test")
def new(request):
print("Hey")
print("cache_page is working")
return HttpResponse("Hello, I am Mohammed")
這是我的redis -cli,
luvpreet@DHARI-Inspiron-3542:~/test_venv_wrapper/test_redis/cache_redis$ redis-cli
127.0.0.1:6379> select 2
OK
127.0.0.1:6379[2]> set "a" "aman"
OK
127.0.0.1:6379[2]> set ":1:a" "theman"
OK
127.0.0.1:6379[2]> keys *
1) "a"
2)":1:views.decorators.cache.cache_page..GET.ad00468064711919773512f81be0dbc4.d41d8cd98f00b204e9800998ecf8427e.en-us.UTC"
3) ":1:posts"
4) ":1:a"
5) ":1:aman"
6) ":1:views.decorators.cache.cache_header.cache_test.ad00468064711919773512f81be0dbc4.en-us.UTC"
7) ":1:views.decorators.cache.cache_header..ad00468064711919773512f81be0dbc4.en-us.UTC"
8) ":1:b"
9)":1:views.decorators.cache.cache_page.cache_test.GET.ad00468064711919773512f81be0dbc4.d41d8cd98f00b204e9800998ecf8427e.en-us.UTC"
10) "aman"
127.0.0.1:6379[2]> get ":1:a"
"theman"
127.0.0.1:6379[2]> get "a"
"aman"
這是對應的redis-cli監視器
luvpreet@DHARI-Inspiron-3542:~/test_venv_wrapper/test_redis/cache_redis$ redis-cli monitor
OK
1491412249.001149 [0 unix:/var/run/redis/redis.sock] "INFO"
1491412249.086196 [0 127.0.0.1:44984] "select" "2"
1491412250.001249 [0 unix:/var/run/redis/redis.sock] "INFO"
1491412257.001426 [0 unix:/var/run/redis/redis.sock] "INFO"
1491412257.423536 [2 127.0.0.1:44984] "set" "a" "aman"
1491412258.001311 [0 unix:/var/run/redis/redis.sock] "INFO"
1491412269.001211 [0 unix:/var/run/redis/redis.sock] "INFO"
1491412269.820886 [2 127.0.0.1:44984] "set" ":1:a" "theman"
1491412270.000741 [0 unix:/var/run/redis/redis.sock] "INFO"
1491412272.955386 [2 127.0.0.1:44984] "keys" "*"
1491412273.001121 [0 unix:/var/run/redis/redis.sock] "INFO"
1491412340.991928 [2 127.0.0.1:44984] "get" ":1:a"
1491412341.002001 [0 unix:/var/run/redis/redis.sock] "INFO"
1491412344.106985 [2 127.0.0.1:44984] "get" "a"
1491412345.001677 [0 unix:/var/run/redis/redis.sock] "INFO"
這意味着可以手動插入數據庫2中的數據,並且可以通過redis-cli進行獲取。
但是,當我嘗試從django-app python shell獲取手動輸入的數據時,就會發生這種情況,
>>> from django.core.cache import cache
>>> cache.get("a")
Traceback (most recent call last):
File "<console>", line 1, in <module>
File "/usr/local/lib/python2.7/dist-packages/redis_cache/backends/base.py", line 33, in wrapped
return method(self, client, key, *args, **kwargs)
File "/usr/local/lib/python2.7/dist-packages/redis_cache/backends/base.py", line 259, in get
value = self.get_value(value)
File "/usr/local/lib/python2.7/dist-packages/redis_cache/backends/base.py", line 210, in get_value
value = self.deserialize(value)
File "/usr/local/lib/python2.7/dist-packages/redis_cache/backends/base.py", line 197, in deserialize
return self.serializer.deserialize(value)
File "/usr/local/lib/python2.7/dist-packages/redis_cache/serializers.py", line 42, in deserialize
return pickle.loads(force_bytes(value))
UnpicklingError: could not find MARK
這是與之相對應的redis-cli監視器,
OK
1491413058.004167 [0 unix:/var/run/redis/redis.sock] "INFO"
1491413059.002746 [0 unix:/var/run/redis/redis.sock] "INFO"
1491413060.663292 [2 unix:/var/run/redis/redis.sock] "GET" ":1:a"
1491413061.001167 [0 unix:/var/run/redis/redis.sock] "INFO"
為什么不能訪問手動寫入的數據? 我知道它為通過django寫入的數據添加了前綴。 前綴是":1:key_name"
。 這就是為什么我添加了兩個鍵,即“ a”和“:1:a”的原因。 這樣,當我嘗試訪問“ a”時,它將調用“:1:a”。
但是出現此錯誤。 因此,它肯定是通過其他方式將數據寫入Redis。 請告訴我有關錯誤的信息,並告訴我其寫入數據的方式。
您得到的錯誤不是數據檢索錯誤,正在檢索數據,但不是正確的泡菜格式。
通過django-redis設置數據時,首先使用cPickle序列化數據,然后將其作為腌制字符串存儲到redis中。
檢索通過django-redis存儲的數據時,會將其檢索為pickle序列化的字符串,然后反序列化為相應的python數據類型。
例:
>>> from django.core.cache import cache
>>> cache.set("THE_KEY","aman")
True
>>> cache.get("THE_KEY")
'aman'
>>>
dhruv@dhruvpathak:~$ redis-cli
127.0.0.1:6379> keys *
1) ":1:THE_KEY"
127.0.0.1:6379> get ":1:THE_KEY"
"\x80\x02U\x04amanq\x01."
127.0.0.1:6379> set "THE_MANUAL_KEY" "aman"
OK
127.0.0.1:6379> get "THE_MANUAL_KEY"
"aman"
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