Wiki

Clone wiki

django-view-cache-utils / Home

Overview

django-view-cache-utils is a django app that provides a method to do advanced view caching. It's basically a patch from http://code.djangoproject.com/ticket/11269 converted to stand-alone python package.

Installation

$ easy_install django-view-cache-utils

or

$ pip install django-view-cache-utils

or

$ hg clone http://bitbucket.org/kmike/django-view-cache-utils/ 
$ cd django-view-cache-utils
$ python setup.py install

Adding 'view_cache_utils' to INSTALLED_APPS is not necessery, it's a simple python package - just import it when needed.

Usage

This package provides ``cache_page_with_prefix`` decorator. It tries to get the page from the cache and populate the cache if the page isn't in the cache yet. Works similar to standard Django cache_page decorator, but accept callable key_prefix. It makes it easier to fine-tune view caching (implement per-user cache, or cache based on GET parameters, or cache based on user cookies - cache based on anything in request).

Example 1

    # 2 static versions of the my_view response: for authenticated and anonymous users
    
    from view_cache_utils import cache_page_with_prefix
    
    def my_key_prefix(request):
        if request.GET:
            return None #magic value to disable caching
    
        if request.user.is_authenticated():
            return 'logged_in'
        else:
            return 'not_logged_in'
    
    @cache_control(must_revalidate=True)  #disable client-side cache because there are 2 versions of page under the same URL
    @cache_page_with_prefix(600, my_key_prefix)
    def my_view(request):
    ....... #something is different for authenticated and anonymous users

Example 2

    #cache my_paginated_view based on "page" parameter in query string
    
    def page_key_prefix(request):
        return request.GET.get('page','')

    @cache_page_with_prefix(60, page_key_prefix)
    def my_paginated_view(request)
    .... #page number is passed via 'page' GET parameter and used for pagination

Notes

CACHE_MIDDLEWARE_KEY_PREFIX is ignored in cache_page_with_prefix by default. It is consistent with existing behaviour of cache_page decorator with key_prefix parameter. If you need it you should prepend your keys with CACHE_MIDDLEWARE_KEY_PREFIX manually.

If you define custom key_prefix function and don't want to cache requests with GET parameters (default behaviour for cache_page) you should do it manually as in example 1. In order to forbid caching key_prefix function should return None value.

If you define key_prefix function that allows several different versions of pages with the same URL you may want to disable client-side cache for that page using @cache_control(must_revalidate=True) decorator as in example.

Updated