Flask Snippets

Snippets are unofficial and unmaintained.

This is an archived view of user-submitted snippets. Despite being hosted on the Flask site, they are not official. No Flask maintainer has curated or checked the snippets for security, correctness, or design.

Adding caching to Flask apps

Posted by Dan Jacob on 2010-05-05 @ 10:26 and filed in Performance

Werkzeug includes a number of caching options in the werkzeug.contrib.cache package: werkzeug.contrib.cache

However the API just handles low-level caching - this is handy for caching individual objects (such as the results of a database query) but not if you want to cache an entire view, or even a whole site.

For a per-view cache we can use a decorator:

from werkzeug.contrib.cache import SimpleCache


cache = SimpleCache()

class cached(object):

    def __init__(self, timeout=None):
        self.timeout = timeout or CACHE_TIMEOUT

    def __call__(self, f):
        def decorator(*args, **kwargs):
            response = cache.get(request.path)
            if response is None:
                response = f(*args, **kwargs)
                cache.set(request.path, response, self.timeout)
            return response
        return decorator

def index():
    return render_template("index.html")

This example uses SimpleCache, for production you probably want to use memcached.

To cache your whole application, you can use before_request and after_request:

def return_cached():
    # if GET and POST not empty
    if not request.values:
        response = cache.get(request.path)
        if response: 
            return response

def cache_response(response):
    if not request.values:
        cache.set(request.path, response, CACHE_TIMEOUT)
    return response

We ignore the cache if the GET or POST are not empty.

You might want to modify these functions further; for example, you might want to ignore the cache in certain views by setting an "ignore_cache" flag in the request or g objects, or if the user is authenticated.

For template-level caching in Jinja2, see this example: Cache Example Extension

This snippet by Dan Jacob can be used freely for anything you like. Consider it public domain.