Robert

Posted on Jun 15, 2022 • Updated on Sep 25, 2022

How to make a Cryptocurrency Telegram bot with Node and Telegraf

#node #javascript #tutorial #beginners

In this post we will learn how to create a cryptocurrency Telegram bot to obtain the values of the cryptocurrency we want to know using Coingecko API.

To make this post I was inspired by this other one How to make a cryptocurrency Telegram bot with Rust and Teloxide be sure to check it out, he creates very good content related to blockchain.

You can contact me by telegram if you need to hire a Full Stack developer or if you want to translate your posts from English to Spanish..

You can clone the repo if you want..

Prerequisites.

Node.js installed.
you will need a Telegram account.

Creating Our Project.

open your terminal and type the following
mkdir node-telegram-tut
cd node-telegram-tut
npm init --y
code .

Dependencies

To install dependencies go to your project folder open a terminal and type the following.

npm i axios dotenv telegraf

Now go to your package.json and add this

  "scripts": {
    "start": "node ./src index.js"
  },

Project File Structure.

node-telegram-tut/
├── node_modules/
├── src/
│ └── index.js
├── .env
└── package.json

Table of Contents.

Setup the Telegram bot Token with BotFather
Coding our Bot
Creating our commands
Deploying it to Heroku
Conclusion

1. Setup the Telegram bot Token with BotFather

To start coding our bot we first need to search for BotFather bot, this one.

After adding it we will see a list of commands, let's click on /newbot you will be prompted to enter the name you wish to give to your bot. I named mine teletutbot, but you are free to call yours whatever you want, as long as the name is available.

After this you will receive a message with your token, now lets set a description for our bot with /setdescription, this way when you add the bot, you will see a message (like a welcome message) describing the bot's function.

Finally you can add a picture if you want with setuserpic, I used this one.

There are more commands to edit your bot, you can try them later.

2. Coding our Bot

Let's start coding our bot, first let's create a .env file in our project root folder, lets add a BOT_TOKEN var and assign it the token given to us by Botfather when we created our bot.

BOT_TOKEN = paste-the-token-here

Now in our index.js, import telegraf, axios and dotenv.

const { Telegraf } = require("telegraf");
const axios = require("axios");
require("dotenv").config();

Then create a bot object from Telegraf Class and pass the BOT_TOKEN.

const bot = new Telegraf(process.env.BOT_TOKEN);

Finally lets create our first bot command that will be /start and then use the launch() method.

bot.command("start", (ctx) => {
  bot.telegram.sendMessage(
    ctx.chat.id,
    "Welcome!!",
    { parse_mode: "html" }
  );
});

bot.launch()

Our code so far should look like this

const { Telegraf } = require("telegraf");
const axios = require("axios");
require("dotenv").config();

const bot = new Telegraf(process.env.BOT_TOKEN);

bot.command("start", (ctx) => {
  bot.telegram.sendMessage(
    ctx.chat.id,
    "Welcome!!",
    { parse_mode: "html" }
  );
});

bot.launch()

3. Creating our commands .

We don't want a bot just to say Welcome, so we need to create more commands, for this example I will create a /help command to get all the available commands, a /currencies command to get all the supported currencies and a /crypto_price to get the price of the selected cryptocurrency in the desired currency.

So let's start creating our /help command.

Let's call our bot object and use the command method, as I said before we're going to name this command help, we are going to use the sendMessage method from telegram api and we need to pass some parameters, there are two required parameters chat_id (extracted from the context) text and I will pass an optional parameter parse_mode to format the text a little bit.

bot.command("help", (ctx) => {
  bot.telegram.sendMessage(
    ctx.chat.id,
    "<b>Command list: </b>\n\n" +
    "<b><i>/currencies</i></b> to get all the suppported currencies. \n\n" +
    '<b><i>/crypto_price</i></b> to get the value of the cryptocurrency in another currency, to use it first type the "currency" and then the "cryptocurrency" e.g. (/crypto_price usd bitcoin), can also add more currencies and cryptos separating them with commas but without spaces e.g. (/crypto_price usd,eur,btc bitcoin,ethereum) \n\n' +
    "",
    { parse_mode: "html" }
  );
});

Now if you start your bot, and type /help you will get this as result.

Now let's create our /currencies command.

Let's go back to our code and create a new command, we will name it currencies, this will send a get request to the coingecko api and retrieve the supported currencies list.

I stored the res.data in a let that I named currencies, also wanted to send the currencies in bold, so I used a map method and returned each currency with *${currency}*, there are other ways to do it.

After that we are going to use again the sendMessage method, and this time wanted to show you that there are a Markdown parse mode. If you want to know more about it, please read the formatting options in the documentation.

bot.command("currencies", (ctx) => {
  axios.get("https://api.coingecko.com/api/v3/simple/supported_vs_currencies")
    .then((res) => {
      if (res) {
        let currencies = res.data;

        //bold currencies text
        let boldedCurrencies = currencies.map((currency) => {
          return `*${currency}*`;
        });

        //send boldedCurrencies and break line
        bot.telegram.sendMessage(
          ctx.chat.id,
          "Supported Currencies" + "\n" + boldedCurrencies.join("\n"),
          {parse_mode: "Markdown"}
        );
      }
    })
    .catch((error) => {
      console.log(error);
    });
});

If you try your /currencies command you should get something similar to this.

Finally we will create the /crypto_price command.

As we did before we will name our new command crypto_price.

For this one as a user we will send a message like this /crypto_price usd,eur bitcoin, so we will split the string by spaces with .split(" "). This should split the string into three parts, the first part will be the /crypto_price, second part usd,eur and third part bitcoin, so we will create two variables currencies and cryptoCurrencies, then we will assign the values respectively.

We need to create a conditional in case the user enters the data incorrectly, or in case the user does not send any data in the command. if this is the case we need to send the user a message, in this case I want him to remember how to use the command so i added an example.

Now we are going to make the GET request to the API, we also going to check if the object from the response is empty, if its empty its because there was a spelling error, or some of the data was misplaced. If this is the case we will answer again telling the user how to use the command.

We are getting the data like this .

data: {
    bitcoin: { usd: 21816, eur: 20872 },
    ethereum: { usd: 1177.46, eur: 1126.54 }
  }

So I chose to use a for loop inside another for loop to manipulate the data, then used again the parse_mode to format the text.

bot.command("crypto_price",  (ctx) => {
  let currencies = ctx.message.text.split(" ")[1];
  let cryptoCurrencies = ctx.message.text.split(" ")[2];

  if (cryptoCurrencies === undefined || currencies === undefined) {
    bot.telegram.sendMessage(
      ctx.chat.id,
      "Please enter the currency and the crypto currency you want to convert to, remember to separate them with commas but without spaces e.g. (/crypto_price usd,eur,btc bitcoin,ethereum) .",
    );
    return;
  }

  axios
    .get(
      `https://api.coingecko.com/api/v3/simple/price?ids=${cryptoCurrencies}&vs_currencies=${currencies}`
    )
    .then((res) => {
      if (res) {

        //if res is empty
        if (Object.keys(res.data).length === 0) {
          bot.telegram.sendMessage(
            ctx.chat.id,
            "Please enter the currency and the crypto currency you want to convert to, remember to separate them with commas but without spaces e.g. (/crypto_price usd,eur,btc bitcoin,ethereum) .",
          );
          return;
        }

        const response = res.data;

        for (let cryptoCurrency in response) {
          for (let currency in response[cryptoCurrency]) {
            bot.telegram.sendMessage(
              ctx.chat.id,
              `<b>${cryptoCurrency}</b> price in <b>${currency.toUpperCase()}</b> ➡️ <b>${response[cryptoCurrency][currency]}</b>`,
              {parse_mode: "html"}
            );
          }
        }

        return;
      } 
    })
    .catch((err) => {
      console.log(err);
    });
});

If you try /crypto_price command, you should get something like this.

4. Deploying it to Heroku .

we need to create a server.

In case you want to deploy this app, we need to create a server, so let's install express with this command npm i express and create a server in our index.js.

Remember to create a port constant and assign this process.env.PORT to it (heroku will give us a port value).

const express = require('express')

//initiaalization
const app = express()

const port = process.env.PORT || 3000;

app.listen(port, () => {
  console.log(`Server is running on port ${port}`);
})