Django per user view caching

Question

I need a per user caching. The regular view caching does unfortunately not support user-based caching.

I tried the template fragment caching like this:

Answer 1

For people using django rest framework and maybe others:

def cache_per_user(timeout):
  def decorator(view_func):
    @wraps(view_func, assigned=available_attrs(view_func))
    def _wrapped_view(request, *args, **kwargs):
        user_id = 'not_auth'
        if request.user.is_authenticated:
            user_id = request.user.id

        return cache_page(timeout, key_prefix="_user_{}_".format(user_id))(view_func)(request, *args, **kwargs)

    return _wrapped_view

  return decorator

Usage:

@method_decorator(cache_per_user(3600))

Answer 2

The following is an improved version for the accepted solution does not consider the request parameters.

decorator_of_cache_per_user.py

from django.core.cache import cache as core_cache

def cache_key(request):
    if request.user.is_anonymous():
        user = 'anonymous'
    else:
        user = request.user.id

    q = getattr(request, request.method)
    q.lists()
    urlencode = q.urlencode(safe='()')

    CACHE_KEY = 'view_cache_%s_%s_%s' % (request.path, user, urlencode)
    return CACHE_KEY

def cache_per_user_function(ttl=None, prefix=None, cache_post=False):
    def decorator(function):
        def apply_cache(request, *args, **kwargs):
            CACHE_KEY = cache_key(request)

            if prefix:
                CACHE_KEY = '%s_%s' % (prefix, CACHE_KEY)

            if not cache_post and request.method == 'POST':
                can_cache = False
            else:
                can_cache = True

            if can_cache:
                response = core_cache.get(CACHE_KEY, None)
            else:
                response = None

            if not response:
                response = function(request, *args, **kwargs)
                if can_cache:
                    core_cache.set(CACHE_KEY, response, ttl)
            return response
        return apply_cache
    return decorator

Answer 3

As of Django >=1.7, using the cache_page along with vary_on_cookie decorators on your view should solve this.

Something like this:

from django.views.decorators.vary import vary_on_cookie
from django.views.decorators.cache import cache_page

@cache_page(60 * 15)
@vary_on_cookie
def view_to_cache(request):
    ...

Take note of the order of decorators as vary_on_cookie should be processed before it gets to cache_page.

Answer 4

I found the solution!

Here is this Portuguese code snippet which works like a charm!

The good thing is that I don't need to fiddle around my template code but can use a clean decorator!

Code is included below

# -*- encoding: utf-8 -*-
'''
Python >= 2.4
Django >= 1.0

Author: eu@rafaelsdm.com
'''
from django.core.cache import cache

def cache_per_user(ttl=None, prefix=None, cache_post=False):
    '''Decorador que faz cache da view pra cada usuario
    * ttl - Tempo de vida do cache, não enviar esse parametro significa que o
      cache vai durar até que o servidor reinicie ou decida remove-lo 
    * prefix - Prefixo a ser usado para armazenar o response no cache. Caso nao
      seja informado sera usado 'view_cache_'+function.__name__
    * cache_post - Informa se eh pra fazer cache de requisicoes POST
    * O cache para usuarios anonimos é compartilhado com todos
    * A chave do cache será uma das possiveis opcoes:
        '%s_%s'%(prefix, user.id)
        '%s_anonymous'%(prefix)
        'view_cache_%s_%s'%(function.__name__, user.id)
        'view_cache_%s_anonymous'%(function.__name__)
    '''
    def decorator(function):
        def apply_cache(request, *args, **kwargs):
            # Gera a parte do usuario que ficara na chave do cache
            if request.user.is_anonymous():
                user = 'anonymous'
            else:
                user = request.user.id

            # Gera a chave do cache
            if prefix:
                CACHE_KEY = '%s_%s'%(prefix, user)
            else:
                CACHE_KEY = 'view_cache_%s_%s'%(function.__name__, user)       

            # Verifica se pode fazer o cache do request
            if not cache_post and request.method == 'POST':
                can_cache = False
            else:
                can_cache = True

            if can_cache:
                response = cache.get(CACHE_KEY, None)
            else:
                response = None

            if not response:
                response = function(request, *args, **kwargs)
                if can_cache:
                    cache.set(CACHE_KEY, response, ttl)
            return response
        return apply_cache
    return decorator