Introduction

This code example demonstrates how to use Python’s Flask framework and the python-telegram-bot library (version 13.0) to build a webhook for a Telegram bot. We will utilize the Google Cloud Run container to handle incoming messages and invoke the bot without long polling.

from flask import Flask, request, jsonify
from telegram import Bot, Update
from telegram.ext import Dispatcher
import requests

app = Flask(__name__)
bot = Bot(token="YOUR_BOT_TOKEN_HERE")
dispatcher = Dispatcher(bot, None, workers=0, use_context=True)

Defining the Message Handler

To handle incoming messages, we define a function called photo_handler that will be used as a handler for photo messages.

def photo_handler(update: Update, context):
    user_id = update.message.from_user.id
    owner_id = 123456789  # Replace with your user_id

    if user_id == owner_id:
        file_id = update.message.photo[-1].file_id  # Get the highest-resolution photo
        file_info = bot.get_file(file_id)
        file_url = file_info.file_path
        
        # Download the file (assuming you have 'requests' installed)
        response = requests.get(file_url)
        with open("received_photo.jpg", "wb") as f:
            f.write(response.content)

Setting up the Webhook Endpoint

We define a route for the /webhook endpoint using the @app.route decorator. This endpoint will receive incoming updates from Telegram.

@app.route('/webhook', methods=['POST'])
def webhook():
    update = Update.de_json(request.get_json(), bot)
    dispatcher.process_update(update)
    return jsonify(success=True)

Adding the Message Handler to the Dispatcher

We add the photo_handler function as a message handler using the MessageHandler class from the telegram.ext module. We specify the Filters.photo filter to only handle photo messages.

if __name__ == "__main__":
    from telegram.ext import MessageHandler, Filters
    
    photo_handler = MessageHandler(Filters.photo, photo_handler)
    dispatcher.add_handler(photo_handler)
    app.run(port=5000)

Conclusion

By using Flask and the python-telegram-bot library, we can easily build a webhook for a Telegram bot. This allows us to handle incoming messages efficiently using a Google Cloud Run container instead of using long polling.