How to receive messages in group chats using telegram bot api

Telegram's Bot API does not support secret chats at the moment. You can read the documentation, but a short explanation is: end-to-end encryption is used in secret chats which is tricky to implement for bots and requires additional work.

There's no word on when it'll be supported, if ever. At any rate, Telegram Bots are generally meant as a useful aid or for fun, not for sensitive things like financial transactions.

In order to get the group chat id, do as follows:

1. Add the Telegram BOT to the group.

2. Get the list of updates for your BOT:

    https://api.telegram.org/bot<YourBOTToken>/getUpdates
   

   Ex:

    https://api.telegram.org/bot123456789:jbd78sadvbdy63d37gda37bd8/getUpdates
   

3. Look for the "chat" object:

{"update_id":8393,"message":{"message_id":3,"from":{"id":7474,"first_name":"AAA"},"chat":{"id":<group_ID>,"title":""},"date":25497,"new_chat_participant":{"id":71,"first_name":"NAME","username":"YOUR_BOT_NAME"}}}

This is a sample of the response when you add your BOT into a group.

4. Use the "id" of the "chat" object to send your messages.

5. (If you created the new group with the bot and you only get {"ok":true,"result":[]}, remove and add the bot again to the group)

6. Private chart only works in image argoprojlabs/argocd-notifications:v1.1.0 or above.