Update

examples/asynchronous_telebot/middleware/i18n.py

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+#!/usr/bin/python
+
+# This example shows how to implement i18n (internationalization) l10n (localization) to create
+# multi-language bots with middleware handler.
+#
+# Also, you could check language code in handler itself too.
+# But this example just to show the work of middlewares.
+
+import telebot
+from telebot.async_telebot import AsyncTeleBot
+from telebot import asyncio_handler_backends
+import logging
+
+logger = telebot.logger
+telebot.logger.setLevel(logging.DEBUG) # Outputs debug messages to console.
+
+TRANSLATIONS = {
+    'hello': {
+        'en': 'hello',
+        'ru': 'привет',
+        'uz': 'salom'
+    }
+}
+
+
+
+bot = AsyncTeleBot('TOKEN')
+
+
+class LanguageMiddleware(asyncio_handler_backends.BaseMiddleware):
+    def __init__(self):
+        self.update_types = ['message'] # Update types that will be handled by this middleware.
+    async def pre_process(self, message, data):
+        data['response'] = TRANSLATIONS['hello'][message.from_user.language_code]
+    async def post_process(self, message, data, exception):
+        if exception: # You can get exception occured in handler.
+            logger.exception(str(exception))
+
+bot.setup_middleware(LanguageMiddleware()) # do not forget to setup
+
+@bot.message_handler(commands=['start'])
+async def start(message, data: dict):
+    # you can get the data in handler too.
+    # Not necessary to create data parameter in handler function.
+    await bot.send_message(message.chat.id, data['response'])
+
+
+bot.polling()