Recently, I learned a trick to make my Telegram bot private to certain users.

I tried not to create the whole CRUD thingy for the membership and after Googling I found out about one of the API provided.

https://core.telegram.org/bots/api#getchatmember

This would allow us to get info of a user with a given chat_id. It can be a channel or a group.

Basically your membership for your bot will be based on the group of your bot and the allowed users are in. So, both of them need to be in the same group/channel.

The code would look like the screenshot.

bot.api.get_chat_member(chat_id: -10012345678, user_id: message.from_id)

There’re a few things to note:

We need to get the channel and id of the group

For group:

Invite https://t.me/RawDataBot and on the first entry, it’ll output some JSON. You can get the group’s ID from message.chat.id.

It should look like -10012345678. Remove the bot after that. But if you don’t trust the bot, you probably need to cook up some new code to get the group ID.

For channel:

Channel is a little bit different, you can use one of the methods mentioned here:

https://stackoverflow.com/questions/33858927/how-to-obtain-the-chat-id-of-a-private-telegram-channel/56546442#56546442

Output

So, what’s the output can we expect? Well for Ruby, we’re expecting hash from the output and var["result"]["status"] will give you the status of the user.

It can be many things, but if it’s left then the user is not a member of the group and that’s what we want to know.

Add the bot to a group/channel

This also means you need to add the bot that’s executing the code to be in the same group as those users that you want to give access to.

So, any users who are in the same group/channel will be allowed to chat with the bot based on the previous output.

Again, a channel is a little bit different, you need to add your bot as the admin, compared to a group that can be added as a normal user.

Exception

Another note, the code will raise an exception if the given chat_id doesn’t exist.

As a summary, with this trick, you don’t have to build the whole CRUD and can reuse the group/channel that you already have (assuming you have one).

That’s it, folks, thanks for reading