Telegram

Telegram is a multi-platform instant messaging system. It treasures the security and privacy of the users. Furthermore, as a flexible platform, Telegram allows developers to create bots. Telegram launches lots of bot APIs for third-party developers to build Telegram bots to serve their own needs in no time.
This guide will focus on major concept of building a Telegram bot by Bottender. For more detail about Telegram bot, please check Official Telegram Bot Introduction.

Requirements

To start building a Telegram Bot, there are two requirements you need to satisfy.

  • Token
  • Webhook URL

Get Token

You have to generate a token by talking to BotFather. It is an official bot which will help you create new bots or change settings for existing ones.
Check Official Telegram Bot Introduction for more details about it.

Webhook URL

Your bot receives updates via an outgoing webhook which is a specific URL. When there are any updates for the bot, Telegram will send an HTTPS request to the webhook URL.

Build Your First Telegram Bot

After setting up the webhook URL and getting the authorization token, you should fill them in telegram-hello-world. The following is part of sample code.

const url = '__FILL_URL_HERE__';

const bot = new TelegramBot({
  accessToken: '__FILL_YOUR_TOKEN_HERE__',
});

Run your server and talk to the Telegram bot. It works!

Full Example

Here is the complete example for telegram-hello-world.

const { TelegramBot } = require('bottender');
const { createServer } = require('bottender/express');

const bot = new TelegramBot({
  accessToken: '__FILL_YOUR_TOKEN_HERE__',
});

bot.onEvent(async context => {
  await context.sendText('Hello World');
});

const server = createServer(bot);

server.listen(5000, () => {
  console.log('server is running on 5000 port...');
});

After running up the bot server, you can use bottender CLI command to setup webhook.

$ bottender telegram webhook set -w <YOUR_WEBHOOK_URL>

Events

Bottender supplies several types of event. You are able to access them via context.event.
For more information, check Event Reference.

Telegram-Specific Context Event

  • isText
  • isPhoto
  • isAudio
  • isVoice
  • isVideo
  • callbackQuery
  • ...

more on TelegramEvent Reference.

Example:

bot.onEvent(async context => {
  if (context.event.isPhoto) {
    await context.sendMessage('I know this is a photo.');
  } else if (
    context.event.callbackQuery === 'A_DEVELOPER_DEFINED_CALLBACK_QUERY'
  ) {
    await context.sendMessage('I know this is a callback query.');
  } else {
    await context.sendMessage('I do not understand.');
  }
});

Send APIs

After your bot receives the request from Telegram, you can use context send APIs to interact with users.

Telegram-Specific Context Send API

  • sendMessage
  • sendPhoto
  • sendVideo
  • sendContact
  • ...

more on TelegramContext Reference.

Example:

bot.onEvent(async context => {
  await context.sendMessage('Hello World!');
  await context.sendPhoto('http://example.com/pic.png');
  await context.sendContact({
    phone_number: '886123456789',
    first_name: 'first name',
  });
});

References