Last lecture you created a bot and tested the raw API
This lecture your bot actually comes alive
It will receive messages and respond to them
We are using aiogram v3 β the most professional bot library in Python
It is fully async, modern, and what production bots are built with
This lecture covers:
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Create a folder for your bot project with this structure:
my_bot/
βββ bot.py
βββ .env
Inside .env β store your token safely:
BOT_TOKEN=1234567890:AAHdqTcvCH1vGWJxfSeofSAs0K5PALDsaw
Never put your token directly in your Python file
Never upload .env to GitHub
Create a .gitignore file and add .env to it
# .gitignore
.env
This is not optional β leaked tokens get your bot hijacked
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Bots need to handle many users at the same time
While waiting for one user's response the bot should not freeze for everyone else
That is what async/await solves
Normal function:
def greet():
print("Hello") # runs and blocks until done
Async function:
async def greet():
print("Hello") # runs without blocking other tasks
await means "do this but let other things run while waiting":
async def handle(message):
await message.reply("Hello!") # sends reply without freezing the bot
In aiogram every handler must be async
Every Telegram API call must be awaited
You will get an error if you forget either
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import asyncio
from aiogram import Bot, Dispatcher
from aiogram.types import Message
from aiogram.filters import Command
import os
from dotenv import load_dotenv
load_dotenv()
TOKEN = os.getenv("BOT_TOKEN")
bot = Bot(token=TOKEN)
dp = Dispatcher()
@dp.message(Command("start"))
async def start_handler(message: Message):
await message.answer(f"Hello {message.from_user.first_name}! I am alive!")
@dp.message(Command("help"))
async def help_handler(message: Message):
await message.answer("I am a bot. Send me a message and I will echo it back.")
@dp.message()
async def echo_handler(message: Message):
await message.answer(message.text)
async def main():
await dp.start_polling(bot)
if name == "main":
asyncio.run(main())
Run this with: python bot.py
Open Telegram, send your bot /start
It responds β your bot is alive
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load_dotenv() β loads your .env file so os.getenv() can read it
Bot(token=TOKEN) β creates the bot object that talks to Telegram
Dispatcher() β the brain of your bot, routes messages to the right handler
@dp.message(Command("start")) β a decorator
It tells the Dispatcher: when someone sends /start, run this function
message.from_user.first_name β the sender's first name
This is the OOP we covered last section β message is an object with attributes
message.answer() β sends a reply to the same chat
message.reply() β sends a reply that quotes the original message
The echo handler at the bottom has no filter
It catches every message that did not match any other handler
Order matters β put specific handlers first, catch-all last
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Watch this for a full visual walkthrough of setting up aiogram v3
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Get the echo bot running then extend it:
from datetime import datetime
@dp.message(Command("time"))
async def time_handler(message: Message):
now = datetime.now().strftime("%H:%M:%S")
await message.answer(f"Current time: {now}")
from aiogram.filters import F
@dp.message(F.text)
async def echo_handler(message: Message):
await message.answer(message.text)
Test all commands, screenshot the responses from your actual bot
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