Starting a telegram bot without using /start command

Question

I am building a telegram bot that shows a main menu upon starting (using /start). Now, every time I want to start the bot I have to write /start but I want to make it that if the user sent anything (without /start) the bot will start and show the main menu again. I did some research and I couldn't figure it out.

Here is my code:

from telegram.ext import CommandHandler, CallbackQueryHandler, Updater
from telegram import InlineKeyboardButton, InlineKeyboardMarkup, ReplyMarkup

API_KEY=''

def start(update, context):
  update.message.reply_text(main_menu_message(),
    reply_markup=main_menu_keyboard())

def main_menu(update,context):
  query = update.callback_query
  query.answer()
  query.edit_message_text(
    text=main_menu_message(),
    reply_markup=main_menu_keyboard())

def main_menu_keyboard():
  keyboard = [[InlineKeyboardButton('Option 1', callback_data='a1'), InlineKeyboardButton('Option 2', callback_data='a2')],
              [InlineKeyboardButton('Option 3', callback_data='a3'), InlineKeyboardButton('Option 4', callback_data='a4')]]
  return InlineKeyboardMarkup(keyboard)

def main_menu_message():
  return 'Hello, How Can I help you??'


updater = Updater(token=API_KEY, use_context=True)
updater.dispatcher.add_handler(CommandHandler('start', start))
updater.start_polling()

We can see the output of this code here

Answer 1

MessageHandler(Filters.all, callback) will handle any message. See here and here .

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Disclaimer: I'm currently the maintainer of python-telegram-bot .