goofansu goofansu - 1 year ago 166
Python Question

Save unicode in redis but fetch error

I'm using mongodb and redis, redis is my cache.

I'm caching mongodb objects with redis-py:

obj in mongodb: {u'name': u'match', u'section_title': u'\u6d3b\u52a8', u'title':
u'\u6bd4\u8d5b', u'section_id': 1, u'_id': ObjectId('4fb1ed859b10ed2041000001'), u'id': 1}

the obj fetched from redis with hgetall(key, obj) is:

{'name': 'match', 'title': '\xe6\xaf\x94\xe8\xb5\x9b', 'section_title':
'\xe6\xb4\xbb\xe5\x8a\xa8', 'section_id': '1', '_id': '4fb1ed859b10ed2041000001', 'id': '1'}

As you can see, obj fetched from cache is str instead of unicode, so in my app, there is error s like :'ascii' codec can't decode byte 0xe6 in position 12: ordinal not in range(128)

Can anyone give some suggestions? thank u

okm okm
Answer Source

Update, for global setting, check jmoz's answer.

If you're using third-party lib such as django-redis, you may need to specify a customized ConnectionFactory:

class DecodeConnectionFactory(redis_cache.pool.ConnectionFactory):
    def get_connection(self, params):
        params['decode_responses'] = True
        return super(DecodeConnectionFactory, self).get_connection(self, params)

Assuming you're using redis-py, you'd better to pass str instead of unicode to Redis, or else Redis will encode it automatically for *set commands, normally in UTF-8. For the *get commands, Redis has no idea about the formal type of a value and has to just return the value in str directly.

Thus, As Denis said, the way that you storing the object to Redis is critical. You need to transform the value to str to make the Redis layer transparent for you.

Also, set the default encoding to UTF-8 instead of using ascii