Support for NX/XX/CH/INCR options to ZADD

[carljm]

Redis 3.0.2+ support NX, XX, CH, and INCR options to the ZADD command: http://redis.io/commands/zadd#zadd-options-redis-302-or-greater

It doesn't seem (from the docs, at least) that redis-py supports these options.

Are you interested in supporting them? Should I bother with a pull request to implement support?

The one API issue is that the use of kwargs in the existing zadd API makes it a bit confusing where to add these options in the API with backward-compatibility. Any thoughts on that?

[andymccurdy]

Hey Carl, good to hear from you.

Ya, the kwargs issue is why I haven't already implemented this. There's a pull request (#638) that implemented each option as a separate command, but that means you can't mix options together.

My current thought is that the existing API sucks (using kwargs) and instead should just take a dict of items along with separate arguments for these options. This unfortunately breaks exiting code and I've been reluctant to bite the bullet.

It's becoming clearer that it's time for redis-py 3.0 where I can fix some of these issues without worrying as much about breaking things.

[carljm]

Hi Andy! Yeah, in practice I find the keys in a sorted set are usually dynamic, not literals, so the kwargs syntax isn't very useful anyway. So 👍 to your plan, and here's to redis-py 3.0 :-)

[AngusP]

Any idea how prevalent the kwargs method for zadd is? I doubt many people at all use it, given it's not very pythonic and as @carljm says, not great with variable keys.

[0v0]

Hi, I found the same issue recently since I just started to use redis with Python.
And I reviewed the comments above considering the preservation of the previous way and the redis updates.
So I have an aggressive suggestion that you may preserve a keyword like "__write_mode__" to that method in kwargs. If that keyword was already used by someone, that guy must be quite boring.

[trickkiste]

Just ran into the same issue.

[id0Sch]

Hi @andymccurdy,
are there updates regarding this issue/version 3.0?
I need to use zadd w/ NX in production.

currently I managed to solve this issue by executing the command manually

pipe.execute_command('ZADD', OTT_REDIS_KEY, 'NX', expiration_time, key)

Would appreciate your reply.
thanks

[Granitosaurus]

You can monkey patch in this functionality:

import redis
from redis import RedisError


def zadd(self, name, items, nx=False, xx=False):
    if nx and xx:
	raise RedisError("ZADD can't use both NX and XX modes")
    pieces = []
    if nx:
	pieces.append('NX')
    if xx:
	pieces.append('XX')
    for pair in items:
	if len(pair) != 2:
	    raise RedisError("ZADD items have to be pairs")
	pieces.append(pair[1])
	pieces.append(pair[0])
    return self.execute_command('ZADD', name, *pieces)

redis.Redis.zadd = zadd

# then you can use
redis.Redis().zadd('my_key', [('foo', 1), ('bar', 2)], nx=True)

I really think this should be updated even if it breaks backwards compatibility because nx and xx settings are very important in set operations.

[foxx]

It would be nice to see this improvement released, as it's surprising behaviour.

[andymccurdy]

fixed in redis-py 3.0