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

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?

[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.

[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.