How to use Flask-Cache with Flask-Restful

Question

How do I use Flask-Cache @cache.cached() decorator with Flask-Restful? For example, I have a class Foo inherited from Resource, and Foo has get, post, put, and delete methods.

How can I can invalidate cached results after a POST?

@api.resource('/whatever') class Foo(Resource):     @cache.cached(timeout=10)     def get(self):         return expensive_db_operation()      def post(self):         update_db_here()          ## How do I invalidate the value cached in get()?         return something_useful() 

Answer 1

As Flask-Cache implementation doesn't give you access to the underlying cache object, you'll have to explicitly instantiate a Redis client and use it's keys method (list all cache keys).

• The cache_key method is used to override the default key generation in your cache.cached decorator.
• The clear_cache method will clear only the portion of the cache corresponding to the current resource.

This is a solution that was tested only for Redis and the implementation will probably differ a little when using a different cache engine.

from app import cache # The Flask-Cache object from config import CACHE_REDIS_HOST, CACHE_REDIS_PORT # The Flask-Cache config from redis import Redis from flask import request import urllib  redis_client = Redis(CACHE_REDIS_HOST, CACHE_REDIS_PORT)  def cache_key():    args = request.args    key = request.path + '?' + urllib.urlencode([      (k, v) for k in sorted(args) for v in sorted(args.getlist(k))    ])    return key  @api.resource('/whatever') class Foo(Resource):      @cache.cached(timeout=10, key_prefix=cache_key)     def get(self):         return expensive_db_operation()      def post(self):         update_db_here()         self.clear_cache()         return something_useful()      def clear_cache(self):         # Note: we have to use the Redis client to delete key by prefix,         # so we can't use the 'cache' Flask extension for this one.         key_prefix = request.path         keys = [key for key in redis_client.keys() if key.startswith(key_prefix)]         nkeys = len(keys)         for key in keys:             redis_client.delete(key)         if nkeys > 0:             log.info("Cleared %s cache keys" % nkeys)             log.info(keys)