How to pass user's id into the decorator as an argument. aiogram

Question

Im writing a simple procedure bot and one of the features requires authorization. Easiest way I found is having an array of telegram user ids and when user wants to execute a command /log it would check if his id is in "admins" list. So I ended up having this:

admins = [123123, 12312]
def is_authorized(user_id):
    def decorator(func):
        @wraps(func)
        def wrapper(*args, **kwargs):
            if user_id in users:
                return func(*args, **kwargs)
            else:
                return
        return wrapper

    return decorator


@dp.message(Command(commands=["log"]))
@is_authorized(message.from_user.id)
async def loglast20(message: types.Message):
    await bot.send_message(message.from_user.id, 'some logs here')

But the problem is

@is_authorized(message.from_user.id)

'message' is not referenced before usage. How do I pass 'message.from_user.id' as an argument to my is_authorized decorator? Im not really into creating class objects or maintaining sessions, i'd like to keep it simple

Answer 1

We cannot affect the handlers by creating decorators directly in the aiogram.

aiogram provides powerful mechanism for customizing event handlers via middlewares.

According to the aiogram documentation, the middleware works as follows

In this case we need inner middleware (Middleware) because our function needs to run after the filter Command(commands=["log"])

Aiogram3 has a marker handler that can be used in this middleware called flags. It is suitable for your situation.

First we need to create middleware.

middleware.py

import logging
from typing import Any, Awaitable, Callable, Dict

from aiogram import BaseMiddleware
from aiogram.dispatcher.flags import get_flag
from aiogram.types import Message, TelegramObject

logger = logging.getLogger(__name__)

ADMINS = [123123, 12312]


class AuthorizationMiddleware(BaseMiddleware):
    """
    Helps to check if user is authorized to use the bot
    """

    async def __call__(
            self,
            handler: Callable[[TelegramObject, Dict[str, Any]], Awaitable[Any]],
            event: TelegramObject,
            data: Dict[str, Any],
    ) -> Any:
        if not isinstance(event, Message):
            return await handler(event, data)

        authorization = get_flag(data, "authorization")
        print("Authorization: ", authorization)
        if authorization is not None:
            if authorization["is_authorized"]:
                if event.chat.id in ADMINS:
                    return await handler(event, data)
                else:
                    return None
        else:
            return await handler(event, data)

bot.py

import asyncio
import logging
import sys

from aiogram import Bot, Dispatcher, types, flags
from aiogram.enums import ParseMode
from aiogram.filters import CommandStart, Command
from aiogram.types import Message, CallbackQuery
from aiogram.utils.markdown import hbold


from middleware import AuthorizationMiddleware

BOT_TOKEN = "Your bot token"

dp = Dispatcher()


@dp.message(CommandStart())
async def command_start_handler(message: Message) -> None:
    await message.answer(f"Hello, {hbold(message.from_user.full_name)}!")


@dp.message(Command(commands=["log"]))
@flags.authorization(is_authorized=True) # You need to write this @flags line after the @dp.message()
async def log_last_20(message: types.Message, bot: Bot):
    await bot.send_message(message.from_user.id, 'some logs here')



async def main() -> None:
    bot = Bot(BOT_TOKEN, parse_mode=ParseMode.HTML)
    dp.message.middleware(AuthorizationMiddleware())
    await dp.start_polling(bot)


if __name__ == "__main__":
    logging.basicConfig(level=logging.INFO, stream=sys.stdout)
    asyncio.run(main())