hset for key=0 raises redis.exceptions.DataError

[AleksMat]

Hi,

In the new redis-py version 3.5.0 I have noticed some additional checks in Redis.hset method. Because of these checks the following corner case now fails:

Redis().hset('my-name', 0, 'my-value')

raising an error redis.exceptions.DataError: 'hset' with no key value pairs.

The problem is in this line where not key check is made.

Potential solutions:

• Changing not key into key is None check. This covers case key=0 but it doesn't raise an error if key='' where it probably should?
• Changing not key into key is None or not str(key) . I think this should cover all cases but it's an additional casting operation.

Let me know if any of these options makes sense. I would be happy to submit a PR for this.

For now, I'll just make sure that I always cast key argument into string in my code to avoid this issue.

[andymccurdy]

It appears that your first suggestion (comparing key to None) is sufficient. It's actually legal in Redis to have an empty string as a key within a hash. A PR would be great, thanks!

In [3]: r.hset('my-hash', mapping={'foo': 'bar'})                                                                                                                                 
Out[3]: 1

# manually sending commands to a connection to avoid the `hset` checks
In [5]: conn = r.connection_pool.get_connection('_')
In [6]: conn.send_command('HSET', 'my-hash', '', 'empty value')
In [7]: conn.read_response()                                                                                                                                                         
Out[7]: 1

# notice the empty string key...
In [8]: r.hgetall('my-hash')                                                                                                                                                      
Out[8]: {b'foo': b'bar', b'': b'empty value'}