aiogram custom filter example

bot.py

import logging
from aiogram import Bot, Dispatcher, executor, types
from aiogram.dispatcher.filters import Filter

logging.basicConfig(level=logging.INFO)
bot = Bot(token="")
dp = Dispatcher(bot)

admins = set()


class IsAdmin(Filter):
    key = "is_admin"

    async def check(self, message: types.Message):
        return message.from_user.id in admins


@dp.message_handler(IsAdmin())
async def only_for_admins(message: types.Message):
    await message.reply("Only for admins!")


@dp.message_handler(commands="make")
async def add_to_admins(message: types.Message):
    admins.add(message.from_user.id)
    await message.reply(f"New admins list: {admins}")


if __name__ == "__main__":
    dp.bind_filter(IsAdmin)
    executor.start_polling(dp, skip_updates=True)