get object from redis without eval?

Question

To get a key from memcache (using pylibmc), you do this:

client.set(key, {'object': 'dictionary'}, time=expire)
client.get(key)

The same in redis is this:

redis.setex(key, expire, {'object': 'dictionary'})
eval(redis.get(key) or 'None')

That last line doesn't look right to me. redis only seems to return strings. Is there a get redis to return the object in the same form that it was put in?

Answer 1

The difference is that while both memcached and redis only support string values, pylibmc serializes the values you send it using pickle, redis-py just converts them to string.

If you want to do the same with redis, you can have your own functions to do the pickling for you.

def set_value(redis, key, value):
    redis.set(key, pickle.dumps(value))

def get_value(redis, key):
    pickled_value = redis.get(key)
    if pickled_value is None:
        return None
    return pickle.loads(pickled_value)

Answer 2

Or you can even subclass Redis:

import pickle
from redis import StrictRedis


class PickledRedis(StrictRedis):
    def get(self, name):
        pickled_value = super(PickledRedis, self).get(name)
        if pickled_value is None:
            return None
        return pickle.loads(pickled_value)

    def set(self, name, value, ex=None, px=None, nx=False, xx=False):
        return super(PickledRedis, self).set(name, pickle.dumps(value), ex, px, nx, xx)

Courtesy: https://github.com/andymccurdy/redis-py/issues/186