Redis - Python example of xadd and xread

Question

Could you give a very simple example of using Redis' xread and xadd in Python ( that displays the type and format of return values form xread and input of xadd)? I've already read many documentation but none of them are in Python.

The Redis doc gives an example:

> XADD mystream * sensor-id 1234 temperature 19.8
1518951480106-0

but If I try in python:

sample = {b"hello":b"12"}
id = r.xadd("mystream", sample)

I get this error:

redis.exceptions.ResponseError: WRONGTYPE Operation against a key holding the wrong kind of value

Answer 1

make sure to flush before running just to make sure that there doesn't exist a list / stream with the same name. :

redis-cli flushall

if __name__ == '__main__':
    r = redis.Redis(host='localhost', port=6379, db=0)
    encoder = JSONEncoder()
    sample = {"hello": encoder.encode([1234,125, 1235, 1235])} # converts list to string
    stream_name = 'mystream'

    for i in range(10):
        r.xadd(stream_name, sample)

    # "$" doesn't seem to work in python
    read_samples = r.xread({stream_name:b"0-0"})