Per View Caching | Caching | Django Tutorial

Introduction

Per-view caching is a technique used in Django to cache the output of individual views. This can significantly improve the performance of your application by reducing the time it takes to generate a response. The cached response is stored for a specified amount of time, and subsequent requests to the same view will return the cached response instead of recalculating it.

Setting Up Caching

To use per-view caching in Django, you need to configure a cache backend. Django supports several cache backends such as Memcached, Redis, and the file-based cache. For the purposes of this tutorial, we'll use the file-based cache.

Example: Configuring File-Based Cache

Add the following configuration to your settings.py file:

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

Implementing Per-View Caching

Once the cache is configured, you can use the @cache_page decorator to cache the output of a view. The decorator takes a single argument, which is the cache timeout (in seconds).

Example: Caching a View for 15 Minutes

Here's how you can cache a view for 15 minutes (900 seconds):

from django.views.decorators.cache import cache_page

@cache_page(900)
def my_view(request):
    # Your view logic here
    return HttpResponse("This is my view")

Advanced Caching Techniques

Django also allows you to use different caches for different views and to vary the cache based on request parameters.

Example: Using Different Caches

You can specify a different cache by using the @cache_page decorator with the cache parameter:

from django.views.decorators.cache import cache_page

@cache_page(900, cache="special_cache")
def my_special_view(request):
    # Your view logic here
    return HttpResponse("This is my special view")

Example: Varying Cache by Request Parameters

You can vary the cache by request parameters using the @vary_on_cookie and @vary_on_headers decorators:

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

@cache_page(900)
@vary_on_cookie
def my_cookie_view(request):
    # Your view logic here
    return HttpResponse("This view varies by cookie")

Clearing the Cache

Sometimes you need to clear the cache manually. You can use the cache API provided by Django to clear the cache or delete specific cache keys.

Example: Clearing the Cache

Here's how you can clear the entire cache:

from django.core.cache import cache

cache.clear()

Or delete a specific cache key:

cache.delete('my_cache_key')

Conclusion

Per-view caching in Django is a powerful technique to improve the performance of your application by reducing the time it takes to generate responses. By configuring the appropriate cache backend and using the @cache_page decorator, you can easily cache the output of your views. Advanced techniques such as using different caches and varying the cache by request parameters provide even more flexibility in managing your application's caching strategy.

Per-View Caching in Django