`MessageHandler` missing 1 update argument

Question

I am doing my first Telebot tutorial, however, I realised that there are some changes with the python telegram bot library and I don't understand the error which I am currently facing.

I tried to send "Hello" to my telebot but it is not responding "Hey" and there is an error in the console. However, when I do /start and /help, it works and the telebot is able to reply me with the intended messages as shown in my code

Here is my code snippet:

from typing import Final
from telegram import Update
from telegram.ext import Application, CommandHandler, MessageHandler, filters, ContextTypes

TOKEN: Final = '6596845905:AAEjzfN0ipLaxcB7Gm6-KnImBVs69p3kPeQ'
BOT_USERNAME: Final = '@langXator_bot'

# Commands

async def start_command(update: Update, context: ContextTypes.DEFAULT_TYPE):
    await update.message.reply_text('Hello! I am a bot')

async def help_command(update: Update, context: ContextTypes.DEFAULT_TYPE):
    await update.message.reply_text('Hello! I am a help')

async def custom_command(update: Update, context: ContextTypes.DEFAULT_TYPE):
    await update.message.reply_text('Hello! I am a custom')

# Responses

def handle_response(text: str) -> str:
    if "Hello" in text:
        return "Hey"
    elif "Bye" in text:
        return "Bye"
    else:
        return "Huh"

async def handle_message(update: Update, context: ContextTypes.DEFAULT_TYPE):
    message_type: str = update.message.chat.type
    text: str = update.message.text.strip()

    print(f'User ({update.message.chat.id}) in {message_type}: "{text}"')

    # differentiate talking in gc and talking in private
    if message_type == 'group':
        if BOT_USERNAME in text:
            new_text: str = text.replace(BOT_USERNAME, '').strip()
            response: str = handle_response(new_text)
        else:
            return
    else:
        response: str = handle_response(text)
    
    print('Bot:', response)
    await update.message.reply_text(response)

async def error(update: Update, context: ContextTypes.DEFAULT_TYPE):
    print(f'Update {update} case error {context.error}')

if __name__ == '__main__':
    print('Starting bot ....')
    app = Application.builder().token(TOKEN).build()

    # Commands (Telegram)
    app.add_handler(CommandHandler('start', start_command))
    app.add_handler(CommandHandler('help', help_command))
    app.add_handler(CommandHandler('custom', custom_command))

    # Messages (Telegram)
    app.add_handler(MessageHandler(filters.Text, handle_message))

    # Errors
    app.add_error_handler(error)

    # Check updates
    print('Polling...')
    app.run_polling(poll_interval=3)  # check every 3 seconds for new messages

Here is the error I received when I sent "Hello" in my telegram bot:

Update Update(message=Message(channel_chat_created=False, chat=Chat(first_name='cxl❄️', id=854959559, type=\<ChatType.PRIVATE\>, username='dobongkimchi'), date=datetime.datetime(2023, 8, 31, 6, 58, 2, tzinfo=datetime.timezone.utc), delete_chat_photo=False, from_user=User(first_name='cxl❄️', id=854959559, is_bot=False, language_code='en', username='dobongkimchi'), group_chat_created=False, message_id=102, supergroup_chat_created=False, text='Hello'), update_id=177020891) case error check_update() missing 1 required positional argument: 'update'

I tried with just one if else statement in handle_response but it doesn't work as well

I suspect it's probably the MessageHandler or the handle_response function

Answer 1

filters.Text is a subclass of BaseFilter, filters.TEXT is an instance of that class and hence an instance of BaseFilter. The first argumet of MessageHandler expects an instance of BaseFilter, not a subclass.

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