django-cache-mock
Use in-process mocks to avoid setting up external caches for Django during
development.
Django has a limited built-in django.core.cache.backends.locmem.LocMemCache
,
to help development, but Django do some magic to always give you a working
connection.
I have some reasons to abuse Django cache this way:
- Thread safety: Django spin one connection per thread to avoid issues with
thread unsafe drivers.
- Good defaults: Django run connections with good defaults.
- Connection reuse: Django already have a pool running and in most cases it is
better to use it.
Install
$ pip install django-cache-mock
Also, it is possible to install with the backends you want.
For mockcache
, it installs mockcache3
,
a fork from original package because it doesn´t work for new versions of Python.
$ pip install django-cache-mock[mockcache]
$ pip install django-cache-mock[fakeredis]
$ pip install django-cache-mock[redislite]
How to use
In your Django settings you already have CACHES
defined.
For memcached
, it's something like that:
CACHES = {
"default": {
"BACKEND": "django.core.cache.backends.memcached.PyMemcacheCache",
"LOCATION": os.getenv("MEMCACHED_HOSTS"),
"OPTIONS": {
"no_delay": True,
"ignore_exc": True,
"max_pool_size": 4,
"use_pooling": True,
},
},
}
Just make a call to django_cache_mock.patch
to replace with a mock backend.
The lib will patch only when cache LOCATION is not defined.
import django_cache_mock
if DEBUG:
django_cache_mock.patch(CACHES, "default", "mockcache")
This patch replace cache with a mocked one. For mockcache,
Custom cache options
The patch
function accepts custom params. It can be used to override mock
behaviours, like the db file redislite
will use, defined by LOCATION
:
django_cache_mock.patch(CACHES, "default", "redislite", {"LOCATION": "data/redis.db"})
Redis backends
Redis has several options to run. This lib implements fakeredis
and redislite
,
with django.core.cache
or django-redis
.
By default, the lib try to maintain the same behavior of the original implementation.
If config uses django-redis
, when you set use backend fakeredis
, it will use
it as fakeredis[django-redis]
.
django_cache_mock.patch(CACHES, "redis", "fakeredis[django-redis]")
django_cache_mock.patch(CACHES, "redis", "redislite[django-redis]")
How to access connections
To get Django memcached and redis clients from cache:
from django.core.cache import caches
def give_me_memcached():
return caches["memcached"]._cache
def give_me_primary_redis():
return caches["redis"]._cache.get_client(write=True)
def give_me_secondary_redis():
return caches["redis"]._cache.get_client()
def give_me_primary_redis():
return caches["redis"].client.get_client()
def give_me_secondary_redis():
return caches["redis"].client.get_client(write=False)