Adding defaults to your bot

Introduction

As of version 12.4, PTB supports passing default values for arguments such as parse_mode to reduce the need for repetition. For this purpose, the Defaults class was introduced. This makes it possible to set defaults for often used arguments. These are set at the creation of the bot and are immutable.

What can be set to a default

parse_mode
disable_notification
disable_web_page_preview
allow_sending_without_reply
do_quote
tzinfo
block
protect_content
link_preview_options

Example

Here is a show case for setting parse_mode to ParseMode.HTML and tzinfo to pytz.timezone('Europe/Berlin') by default:

import logging

import datetime as dtm
import zoneinfo

from telegram.constants import ParseMode
from telegram.ext import MessageHandler, filters, Defaults, Application

logging.basicConfig(
    format='%(asctime)s - %(name)s - %(levelname)s - %(message)s', level=logging.INFO
)


async def job(context):
    chat_id = context.job.chat_id
    timezone = context.bot.defaults.tzinfo
    local_now = dtm.datetime.now(timezone)
    utc_now = dtm.datetime.now(dtm.UTC)
    text = f'Running job at {local_now} in timezone {timezone}, which equals {utc_now} UTC.'
    await context.bot.send_message(chat_id=chat_id, text=text)


async def echo(update, context):
    text = update.message.text
    # Send with default parse mode
    await update.message.reply_text(f'<b>{text}</b>')
    # Override default parse mode locally
    await update.message.reply_text(f'*{text}*', parse_mode=ParseMode.MARKDOWN)
    # Send with no parse mode
    await update.message.reply_text(f'*{text}*', parse_mode=None)

    # Schedule job
    context.job_queue.run_once(
        job, dtm.datetime.now() + dtm.timedelta(seconds=1), chat_id=update.effective_chat.id
    )


def main():
    """Instantiate a Defaults object"""
    defaults = Defaults(parse_mode=ParseMode.HTML, tzinfo=zoneinfo.ZoneInfo('Europe/Berlin'))

    application = (
        Application.builder()
        .token("TOKEN")
        .defaults(defaults)
        .build()
    )

    # on non command text message - echo the message on Telegram
    application.add_handler(MessageHandler(filters.TEXT & ~filters.COMMAND, echo))

    # Start the Bot
    application.run_polling()


if __name__ == '__main__':
    main()