This entry covers how to enable page level caching in Django. We'll be using a dummy cache backend for development, and the file based store for production. Memcached would be faster, but I'm on a memory limited VPS.

settings_common.py

In have a common settings file that is shared between production and development. For this, I added the following three cache settings:

CACHE_MIDDLEWARE_ALIAS = 'progperc'
CACHE_MIDDLEWARE_SECONDS = 60 * 15          # 15 minute cache
CACHE_MIDDLEWARE_ANONYMOUS_ONLY = True

CACHE_MIDDLEWARE_ALIAS sets the key to use for the site in the cache. CACHE_MIDDLEWARE_SECONDS defines how long to cache for. CACHE_MIDDLEWARE_ANONYMOUS_ONLY means that only anonymous users are served pages from the cache. Logged in users will bypass the cache, which is what we want - they will have dynamic features on the page tailored to their user.

Middleware classes also needs changing to add UpdateCacheMiddleware and FetchCacheMiddleware. I ended up with the following list:

MIDDLEWARE_CLASSES = (
    'django.middleware.csrf.CsrfViewMiddleware',
    'django.middleware.cache.UpdateCacheMiddleware',
    'django.contrib.sessions.middleware.SessionMiddleware',
    'django.middleware.locale.LocaleMiddleware',
    'django.contrib.auth.middleware.AuthenticationMiddleware',
    'django.middleware.transaction.TransactionMiddleware',
    'django.middleware.common.CommonMiddleware',
    'django.middleware.doc.XViewMiddleware',
    'django.middleware.cache.FetchFromCacheMiddleware',
)

settings_dev.py

In development, we set the cache to use a dummy back end.

CACHES = {
    'default': {
        'BACKEND': 'django.core.cache.backends.dummy.DummyCache',
    }

}

The above setting is for Django 1.3. For Django 1.2 use:

CACHE_BACKEND = 'dummy://'

settings_live.py

In production, we set the cache to use a directory on disk. This directory needs to be writable by the user that is running the web server.

CACHES = {
    'default': {
        'BACKEND': 'django.core.cache.backends.filebased.FileBasedCache',
        'LOCATION': '/var/site_cache',
    }
}

The above setting is for Django 1.3. For Django 1.2 use:

CACHE_BACKEND = 'file:///var/site_cache'

References

• https://docs.djangoproject.com/en/dev/topics/cache/