How to cache SQL Alchemy calls with Flask-Cache and Redis?

You don't need to create custom RedisCache class. The docs is just teaching how you would create new backends that are not available in flask-cache. But RedisCache is already available in werkzeug >= 0.7, which you might have already installed because it is one of the core dependencies of flask.

This is how I could run the flask-cache with redis backend:

import time
from flask import Flask
from flask_cache import Cache

app = Flask(__name__)
cache = Cache(app, config={'CACHE_TYPE': 'redis'})

@cache.memoize(timeout=60)
def query_db():
    time.sleep(5)
    return "Results from DB"

@app.route('/')
def index():
    return query_db()

app.run(debug=True)

The reason you're getting "ImportError: redis is not a valid FlaskCache backend" is probably because you don't have redis (python library) installed which you can simply install by:
pip install redis.

your redis args would look something like this:

cache = Cache(app, config={
    'CACHE_TYPE': 'redis',
    'CACHE_KEY_PREFIX': 'fcache',
    'CACHE_REDIS_HOST': 'localhost',
    'CACHE_REDIS_PORT': '6379',
    'CACHE_REDIS_URL': 'redis://localhost:6379'
    })

Putting the @cache.memoize over a method that grabs the info from the DB should work.