Simple Slack API client made with Python

I think the Official Python Client for Slack API is well done, but for some reason I need to use the Slack API from Python without using it. I wrote my own Slack client in a super-simple way.

import urllib.request
import json

class SlackAPI:
    
    def __init__(self, token: str, api_base: str = 'https://slack.com/api/'):
        self.token = token
        self.api_base = api_base
    
    def __call__(self, name: str, charset: str = 'utf-8', **kwargs) -> dict:
        req = urllib.request.Request(
            url = self.api_base + name,
            data = json.dumps(kwargs).encode(charset),
            headers = {
                'Authorization': f'Bearer {self.token}',
                'Content-Type': f'application/json; charset={charset}',
            })
        with urllib.request.urlopen(req) as res:
            return json.load(res)
    
    def __getitem__(self, key: str):
        return lambda **kwargs: self(key, **kwargs)

You can use it like this.

token = 'xoxb-000000000000-0000000000000-xxxxxxxxxxxxxxxxxxxxxxxx'
slack_api = SlackAPI(token)

#Get user list
slack_api['users.list']()

#Post a message
slack_api['chat.postMessage'](channel='XXXXXXXXX',text='Yo!',as_user=True)

Of course, you can't use the RTM API, but if it's a Web API, you can probably do it with this. (I haven't tried so many things, so please comment if you can't run this API.)

Postscript (2020.05.18)

[Comment](# comment-a97ebf6ddf92cfa5447a) pointed out that some APIs do not support the JSON request body, so I tried to support it.

import urllib.request
import json

class SlackAPI:

    def __init__(self, token: str, api_base: str = 'https://slack.com/api/'):
        self.token = token
        self.api_base = api_base

    def __getitem__(self, key: str):
        return lambda **kwargs: self.post(key, **kwargs)

    def get(self, name: str, **kwargs) -> dict:
        req = urllib.request.Request(
            url = self.api_base + name + '?' + urllib.parse.urlencode(kwargs),
            headers = {
                'Authorization': f'Bearer {self.token}',
            })
        with urllib.request.urlopen(req) as res:
            return json.load(res)

    def post(self, name: str, charset: str = 'utf-8', **kwargs) -> dict:
        req = urllib.request.Request(
            url = self.api_base + name,
            data = json.dumps(kwargs).encode(charset),
            headers = {
                'Authorization': f'Bearer {self.token}',
                'Content-Type': f'application/json; charset={charset}',
            })
        with urllib.request.urlopen(req) as res:
            return json.load(res)

If you explicitly use the get method, send the data with ʻapplication / x-www-form-urlencoded`.

slack_api.get('conversations.list', limit=20)