python之django-redis 无效的数据库索引错误和 redis url 的含义

我正在使用 django-redis:https://niwinz.github.io/django-redis/latest/

在设置和测试缓存时，我有一个问题。

来自:https://niwinz.github.io/django-redis/latest/#_installation

有这样的代码:

CACHES = { 
    "default": { 
        "BACKEND": "django_redis.cache.RedisCache", 
        "LOCATION": "redis://127.0.0.1:6379/1", 
        "OPTIONS": { 
            "CLIENT_CLASS": "django_redis.client.DefaultClient", 
        } 
    } 
} 

当我使用这个不变的任何 LOCATION 代码作为:"LOCATION": "redis://127.0.0.1:6379/1" 时，它正在做出色地。甚至 "LOCATION": "redis://127.0.0.1:6379/2" 似乎也能正常工作。

但如果我将其更改为 "LOCATION": "redis://127.0.0.1:6379/220",

它返回无效的数据库索引错误。

问题:

1. 为什么会这样？

2. "LOCATION": "redis://127.0.0.1:6379/parameter" 中的参数是什么意思？

这是回溯:

Environment: 
 
 
Request Method: GET 
Request URL: http://127.0.0.1:8000/test/ 
 
Django Version: 2.0.2 
Python Version: 3.6.3 
Installed Applications: 
['django.contrib.admin', 
 'django.contrib.auth', 
 'django.contrib.contenttypes', 
 'django.contrib.sessions', 
 'django.contrib.messages', 
 'django.contrib.staticfiles', 
 'post', 
 'website'] 
Installed Middleware: 
['django.middleware.security.SecurityMiddleware', 
 'django.contrib.sessions.middleware.SessionMiddleware', 
 'django.middleware.common.CommonMiddleware', 
 'django.middleware.csrf.CsrfViewMiddleware', 
 'django.contrib.auth.middleware.AuthenticationMiddleware', 
 'django.contrib.messages.middleware.MessageMiddleware', 
 'django.middleware.clickjacking.XFrameOptionsMiddleware', 
 'django.middleware.cache.UpdateCacheMiddleware', 
 'django.middleware.common.CommonMiddleware', 
 'django.middleware.cache.FetchFromCacheMiddleware'] 
 
 
 
Traceback: 
 
File "D:\pythonDev\interpreters\forMultichat\lib\site-packages\django_redis\cache.py" in _decorator 
  32.             return method(self, *args, **kwargs) 
 
File "D:\pythonDev\interpreters\forMultichat\lib\site-packages\django_redis\cache.py" in get 
  81.                                    client=client) 
 
File "D:\pythonDev\interpreters\forMultichat\lib\site-packages\django_redis\client\default.py" in get 
  204.             raise ConnectionInterrupted(connection=client, parent=e) 
 
During handling of the above exception (Redis ResponseError: invalid DB index), another exception occurred: 
 
File "D:\pythonDev\interpreters\forMultichat\lib\site-packages\django\core\handlers\exception.py" in inner 
  35.             response = get_response(request) 
 
File "D:\pythonDev\interpreters\forMultichat\lib\site-packages\django\utils\deprecation.py" in __call__ 
  93.             response = self.process_request(request) 
 
File "D:\pythonDev\interpreters\forMultichat\lib\site-packages\django\middleware\cache.py" in process_request 
  133.         cache_key = get_cache_key(request, self.key_prefix, 'GET', cache=self.cache) 
 
File "D:\pythonDev\interpreters\forMultichat\lib\site-packages\django\utils\cache.py" in get_cache_key 
  360.     headerlist = cache.get(cache_key) 
 
File "D:\pythonDev\interpreters\forMultichat\lib\site-packages\django_redis\cache.py" in _decorator 
  39.             raise e.parent 
 
File "D:\pythonDev\interpreters\forMultichat\lib\site-packages\django_redis\client\default.py" in get 
  202.             value = client.get(key) 
 
File "D:\pythonDev\interpreters\forMultichat\lib\site-packages\redis\client.py" in get 
  976.         return self.execute_command('GET', name) 
 
File "D:\pythonDev\interpreters\forMultichat\lib\site-packages\redis\client.py" in execute_command 
  667.             connection.send_command(*args) 
 
File "D:\pythonDev\interpreters\forMultichat\lib\site-packages\redis\connection.py" in send_command 
  610.         self.send_packed_command(self.pack_command(*args)) 
 
File "D:\pythonDev\interpreters\forMultichat\lib\site-packages\redis\connection.py" in send_packed_command 
  585.             self.connect() 
 
File "D:\pythonDev\interpreters\forMultichat\lib\site-packages\redis\connection.py" in connect 
  493.             self.on_connect() 
 
File "D:\pythonDev\interpreters\forMultichat\lib\site-packages\redis\connection.py" in on_connect 
  567.             if nativestr(self.read_response()) != 'OK': 
 
File "D:\pythonDev\interpreters\forMultichat\lib\site-packages\redis\connection.py" in read_response 
  629.             raise response 
 
Exception Type: ResponseError at /test/ 
Exception Value: invalid DB index 

请您参考如下方法:

默认情况下，Redis 服务器配置有 16 (0..15) 个共享数据库。使用数据库 0 以外的任何东西通常被认为是不好的做法。