reddish - a friendly redis client with sync and async api

• Features
• Installation
• Minimal Example
• Usage

Features

• both sync and async API
• bring your own connection - supports TCP, TCP+TLS and Unix domain sockets
• supports multiple networking libaries and event loops
  • sync API using the standard library socket module
  • async API using asyncio's, trio's or anyio's stream primitives
• minimal API so you don't have to relearn how to write redis commands
• supports allmost every redis command (including modules) except for SUBSCRIBE, PSUBSCRIBE, SSUBSCRIBE, MONITOR and CLIENT TRACKING ¹
• parses replies into python types if you like (powered by pydantic)
• works with every redis version and supports both RESP2and RESP3 protocols

Installation

pip install reddish  # install just with support for socket and asyncio
pip install reddish[trio]  # install with support for trio
pip install reddish[anyio]  # install with support for anyio

Minimal Example - sync version

import socket
from reddish import Command
from reddish.clients.socket import Redis

redis = Redis(socket.create_connection(('localhost', 6379)))

assert b'PONG' == redis.execute(Command('PING'))

Minimal Example - async version (asyncio)

import asyncio
from reddish.clients.asyncio import Redis

redis = Redis(await asyncio.open_connection('localhost', 6379))

assert b'PONG' == await redis.execute(Command('PING'))

Minimal Example - async version (trio)

import trio
from reddish.clients.trio import Redis

redis = Redis(await trio.open_tcp_stream('localhost', 6379))

assert b'PONG' == await redis.execute(Command('PING'))

Minimal Example - async version (anyio)

import trio
from reddish.backends.anyio import Redis

redis = Redis(await anyio.connect_tctp('localhost', 6379))

assert b'PONG' == await redis.execute(Command('PING'))

Usage

Command with a fixed number of arguments

# simple command without any arguments
Command('PING')

# commands with positional arguments
Command('ECHO {}', 'hello world')

# commands with keyword arguments
Command('SET {key} {value}', key='foo', value=42)

Handling invalid commands

from reddish import CommandError

try:
    await redis.execute(Command("foo"))
except CommandError as error:
    print(error.message)  # >>> ERR unknown command `foo`, with args beginning with:

Parsing replies

# return response unchanged from redis
assert b'42' == await redis.execute(Command('ECHO {}', 42))

# parse response as type
assert 42 == await redis.execute(Command('ECHO {}', 42).into(int))

# handling replies that won't parse correctly
from reddish import ParseError

try:
    await redis.execute(Command('PING').into(int))
except ParseError as error:
    print(error.reply)

# use any type that works with pydantic
from pydantic import Json
import json

data = json.dumps({'alice': 30, 'bob': 42})
response == await redis.execute(Command('ECHO {}', data).into(Json))
assert response == json.loads(data)

Commands with variadic arguments

from reddish import Args

# inlining arguments
Command('DEL {keys}', keys=Args(['foo', 'bar']))  # DEL foo bar

# inlining pairwise arguments 
data = {'name': 'bob', 'age': 42}
Command('XADD foo * {fields}', fields=Args.from_dict(data))  # XADD foo * name bob age 42

Pipelining commands

foo, bar = await redis.execute_many(Command('GET', 'foo'), Command('GET', 'bar'))

# handling errors in a pipeline
from reddish import PipelineError

try:
    foo, bar = await redis.execute_many(*commands)
except PipelineError as error:
    for outcome in error.outcomes:
        try:
            # either returns the reply if it was successful 
            # or raises the original exception if not
            value = outcome.unwrap() 
            ...
        except CommandError:
            ...
        except ParseError:
            ...

Transactions

from reddish import MultiExec

tx = MultiExec(
    Command('ECHO {}', 'foo'),
    Command('ECHO {}', 'bar')
)

foo, bar = await redis.execute(tx)

# handling errors with transactions
try:
    await redis.execute(some_tx)
except CommandError as error:
    # The exception as a whole failed and redis replied with an EXECABORT error
    cause = error.__cause__  # original CommandError that caused the EXECABORT
    print(f'Exception aborted due to {cause.code}:{cause.message}')
except TransactionError as error:
    # Some command inside the transaction failed 
    # but the transaction as a whole succeeded
    # to get at the partial results of the transaction and the errors 
    # you can iterate over the outcomes of the transaction
    for outcome in error.outcomes:
        try:
            outcome.unwrap()  # get the value or raise the original error
        except CommandError:
            ...
        except ParseError:
            ...


# pipelining together with transactions
[foo, bar], baz = await redis.execute_many(tx, Command('ECHO {}', 'baz'))

# handling errors with transactions inside a pipeline
try:
    res: list[int] = await redis.execute_many(*cmds)
except PipelineError as error:
    # handle the outcomes of the pipeline
    for outcome in error.outcomes:
        try:
            outcome.unwrap()
        except CommandError:
            ...
        except ParseError:
            ...
        except TransactionError as tx_error:
            # handle errors inside the transaction
            for tx_outcome in tx_error.outcomes:
                ...

Footnotes

1. Commands like SUBSCRIBE or MONITOR take over the redis connection for listening to new events barring regular commands from being issued over the connection. ↩