Add extension methods to cache

1. Install cache extension by pip::

   pip install django-cache-extension

2. For redis backend use cache like this::

   config your cache file backend to cache_extension:

   CACHES={
         "default": {
             'BACKEND': 'cache_extension.backends.redis.ExtensionRedisBackend',
             'LOCATION': 'redis://redis:6379/0',
             'TIMEOUT': '172800',
             "KEY_PREFIX": "cache_extension",
             'OPTIONS': {
                 "DB": 0,
                 "CLIENT_CLASS": "django_redis.client.DefaultClient",
                 'PARSER_CLASS': 'redis.connection.HiredisParser',
                 'PICKLE_VERSION': 2,
             }
         }
     },
   

3. For custom cache backend::

   from cache_extension.cache import ExtensionCache
   from some_module import CustomCache
   class ExtensionCustomCache(ExtensionCache, CustomCache):
       pass
   

4. Use extension cache methods::

   cache.get_model(Article, pk=1)
   cache.get_models(Article, [1,2,3])
   cache.get_model(UserArticle, user_id=1, article_id=1)
   cache.get_model_list(UserArticle, user_id=1)
   

5. Built in cached fields: ForeignKeyField, OneToOneField. Say you have two models defined as below:

   from django.db import models
   from cache_extension import cached_fields
   
   
   class Foo(models.Model):
       pass
   
   class Bar(models.Model):
       foo = cached_fields.ForeignKeyField(Foo)
   
   

   Then instances of Bar will have a cached_foo property which will try to fetch foo from cache first, if cache misses, will fallback to database.

   bar = Bar.objects.get(pk=1)
   bar.cached_foo # cached foreign field, really handy