#PDF #EPUB #TelegramBot #Python #SQLite #Project

Lesson: Building a PDF <> EPUB Telegram Converter Bot

This lesson walks you through creating a fully functional Telegram bot from scratch. The bot will accept PDF or EPUB files, convert them to the other format, and log each transaction in an SQLite database.

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Part 1: Prerequisites & Setup

First, we need to install the necessary Python library for the Telegram Bot API. We will also rely on Calibre's command-line tools for conversion.

Important: You must install Calibre on the system where the bot will run and ensure its ebook-convert tool is in your system's PATH.

pip install python-telegram-bot==20.3

#Setup #Prerequisites

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Part 2: Database Initialization

We'll use SQLite to log every successful conversion. Create a file named database_setup.py and run it once to create the database file and the table.

# database_setup.py
import sqlite3

def setup_database():
    conn = sqlite3.connect('conversions.db')
    cursor = conn.cursor()
    
    # Create table to store conversion logs
    cursor.execute('''
        CREATE TABLE IF NOT EXISTS conversions (
            id INTEGER PRIMARY KEY AUTOINCREMENT,
            user_id INTEGER NOT NULL,
            original_filename TEXT NOT NULL,
            converted_filename TEXT NOT NULL,
            conversion_type TEXT NOT NULL,
            timestamp DATETIME DEFAULT CURRENT_TIMESTAMP
        )
    ''')
    
    conn.commit()
    conn.close()
    print("Database setup complete. 'conversions.db' is ready.")

if __name__ == '__main__':
    setup_database()

#Database #SQLite #Initialization

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Part 3: The Main Bot Script - Imports & Basic Commands

Now, let's create our main bot file, converter_bot.py. We'll start with imports and the initial /start and /help commands.

# converter_bot.py
import logging
import os
import sqlite3
import subprocess
from telegram import Update
from telegram.ext import Application, CommandHandler, MessageHandler, filters, ContextTypes

# Enable logging
logging.basicConfig(format='%(asctime)s - %(name)s - %(levelname)s - %(message)s', level=logging.INFO)

# --- Bot Token ---
TELEGRAM_TOKEN = "YOUR_TELEGRAM_BOT_TOKEN"

# --- Command Handlers ---
async def start(update: Update, context: ContextTypes.DEFAULT_TYPE) -> None:
    user = update.effective_user
    await update.message.reply_html(
        rf"Hi {user.mention_html()}! Send me a PDF or EPUB file to convert.",
    )

async def help_command(update: Update, context: ContextTypes.DEFAULT_TYPE) -> None:
    await update.message.reply_text("Simply send a .pdf file to get an .epub, or send an .epub file to get a .pdf. Note: Conversion quality depends on the source file's structure.")

#TelegramBot #Python #Boilerplate

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Part 4: The Core Conversion Logic

This function will be the heart of our bot. It uses the ebook-convert command-line tool (from Calibre) to perform the conversion. It's crucial that Calibre is installed correctly for this to work.