Node-telegram-bot-api: Bot that answers in your language

[Cm-8]

Introduction

I have not found documentation about it:
If you need a BOT that reply in the language of the users you can use:
https://github.com/yagop/node-telegram-bot-api, with
https://github.com/mashpie/i18n-node

Question

But Telegram for some user return language code it and fot other it-IT.
Example:

• if I use Telegram mobile app i get: "it"
• if I use Telegram webapp (with chrome) i get: "it-IT"

How can i fix it?

My Code:

process.env.NTBA_FIX_319 = 1;   // fix cancellation of promises https://github.com/yagop/node-telegram-bot-api/issues/319. module.js:652:30

const TelegramBot = require('node-telegram-bot-api');
const token = 'XXXXXXXXX';    // Token from @BotFather
const bot = new TelegramBot(token, {polling: true});    // Create a bot that uses 'polling' to fetch new updates

const botName = "yourBOTName"
const botVer = "1.1.0"

var i18n = require('./node_modules/i18n'),
    app;

i18n.configure({
  locales: ['en-EN', 'it-IT'],
  directory: __dirname + '/locales',
  autoReload: true,
  fallbacks:{'nl-NL': 'en-EN'},
  defaultLocale: 'en-EN'
});


// Test Language
bot.onText(/\/test_i18n/, (msg) => {

    i18n.setLocale(msg.from.language_code);

    var greeting = i18n.__('Hello {{name}}, how are you today?', { name: msg.from.first_name });

    bot.sendMessage(msg.chat.id, greeting, {
            parse_mode: "HTML"
        }
    );
}); 

// Start Message i18n
bot.onText(/\/start_i18n/, (msg) => {

    i18n.setLocale(msg.from.language_code);

    var msg_start_1 = i18n.__("Welcome You {{name}}, \nI'm <b>Your BOT</b> and I'm here to help you to find ...", { name: msg.from.first_name });
    var msg_start_2 = i18n.__("\n\nPlease type: \n<b>The name of ...</b>, or\n/list  -  To know the list of... \n/help -  To have support\n/site  -  To visit our website");

    bot.sendMessage(msg.chat.id, msg_start_1 + msg_start_2, {
            parse_mode: "HTML"
        }
    );
}); 

[jejopl]

If you have a problem only with it and it-IT, you can use simple if/else statement

var lang;

if(msg.from.language_code.length == 2) {
    lang = msg.from.language_code + '-' + msg.from.language_code.toUpperCase();
} else {
    lang = msg.from.language_code;
}

i18n.setLocale(lang);

This way lang will be always it-IT when you will receive it or it-IT

[Cm-8]

Thanks @jejopl,

I was trying a reverse solution :)

    var str = msg.from.language_code.toLowerCase();
    var code = str.substring(0, 2);
    i18n.setLocale(code);

this always returns it (and i've changed the cfg of i18n)

[jejopl]

No problem. Also, you should check at the beginning if msg.from.language_code is not undefined.

[sidelux]

Consider that with custom client not always language_code is valid or exists.

[Cm-8]

@jejopl, @sidelux thank you for the tip!

i18n in configuration allows you to set a default language, so in case of an empty field or undefined it should show the language set.
But it is better to avoid errors in the logic and insert a check on the presence nad of the value of msg.from.language_code:

New code:

i18n.configure({
    locales: ['en', 'it'],
    directory: __dirname + '/locales',
    autoReload: true,
    fallbacks:{'nl': 'en'},
    defaultLocale: 'en'
});


// Test Language
bot.onText(/\/test_i18n/, (msg) => {

    if (msg.from.hasOwnProperty('language_code') && msg.from.language_code!=('undefined')) {
        var str = msg.from.language_code.toLowerCase();
        var code = str.substring(0, 2);
        i18n.setLocale(code);
    }

    var greeting = i18n.__('Hello {{name}}, how are you today?', { name: msg.from.first_name });

    bot.sendMessage(msg.chat.id, greeting, {
            parse_mode: "HTML"
        }
    );
});

[kamikazechaser]

Question seems to have been resolved, closing it for now.

[objNameGit]

hello. How does telegram determine language_code ?
i set spanish language (sp) on windows version telegram app, but language_code = 'en'.
how it work?

[ImTheDeveloper]

Do language codes exist for all clients? Noticing from 520k users that only about 52k have codes set in my tracking. Anyone else seeing the same?

[sidelux]

Yes, is not in all clients, and in some cases it's "en" also I language is different.
I think the best method should be that the user select his language, not auto detecting it.