Telegram Channel Data Retrieval Guide

Japanese Edition
https://daisuke.masuda.tokyo/article-2025-11-08-0057

This slide deck is a technical guide to fully archiving admin posts from a Telegram channel while also monitoring new posts in real time. It explains the differences between the MTProto client APIs (Telethon / Pyrogram) and the Bot API, how to authenticate, how to retrieve message history using methods like messages.getHistory and iter_messages, and how to monitor updates via webhooks, long polling, or Telethon events. It also introduces workflow examples using n8n for saving to a database, cross-posting, and alerts, plus best practices for production such as handling rate limits and backing off when FloodWait errors occur.

Transcript

1. November 7, 2025 Channel Example: t.me/+DKcwQbX3QRphMjFk TELEGRAM CHANNEL DATA RETRIEVAL GUIDE Fetching Historical Posts & Monitoring Real-time Updates • How to fetch all administrator posts from Telegram Channels with complete history • Real-time monitoring techniques for capturing new channel posts as they appear • Technical approaches for developers using Telegram API & libraries
2. OVERVIEW & USE CASES What you can collect: Channel content: Text posts, photos, videos, documents, polls, links Metadata: Post date, views count, forwards, author signatures Edit history: Track modifications to existing posts API Families: MTProto Client API (Telethon, Pyrogram, TDLib) Bot API (HTTP-based, simpler but limited) This presentation covers: Historical backfill of all posts (complete archive) Real-time capture of new posts as published Authentication, permissions, and rate limits Production best practices & code examples API COMPARISON  MTProto Client API Full access to channel history Join any public channel via username Join private channels with invite links Requires user authentication  Bot API Simple HTTP requests Real-time updates via webhooks/polling No historical access to messages Requires bot to be channel admin COMMON USE CASES  Research & Archiving Complete data preservation for analysis  Analytics & Dashboards Track engagement and content performance  Alerts & Monitoring Real-time notifications for new content  Content Moderation Automated filtering and compliance checks 2
3. API AUTHENTICATION & SETUP Authentication Options: Telegram offers two API paths with different authentication requirements and capabilities. MTProto (Telethon/Pyrogram): Requires user account authentication • Register app at my.telegram.org/auth to get api_id and api_hash • Create session file with phone number verification (once) • Join channels via @username or invite link Bot API: Simplified HTTP interface for bots • Create bot via @BotFather to receive token • Add bot as administrator to target channel • Configure webhooks or use getUpdates polling Access & Permissions: MTProto: Full historical access, but requires user account Bot API: Only sees posts after being added as admin messages.getHistory is user-only (not available to bots) Private channels require membership/invitation AUTHENTICATION FLOWS  MTProto Setup 1 Register app at my.telegram.org 2 Save api_id (int) and api_hash (string) 3 Initialize client with credentials 4 Login with phone number (creates session) 5 Join target channel if needed  Bot API Setup 1 Talk to @BotFather on Telegram 2 Create new bot (/newbot) 3 Receive HTTP API token 4 Add bot as admin to channel 5 Configure webhook or polling REQUIRED PERMISSIONS Bot as Channel Admin: Enable these permissions to receive posts: Post Messages Edit Messages Delete Messages Read Messages Note: For complete channel history, use MTProto client API as bots cannot access messages posted before they joined. 3
4. HISTORICAL POSTS RETRIEVAL MTProto Methods: Access the complete history of channel posts using official API methods. messages.getHistory: Primary method for paginating through all posts Parameters: peer, offset_id, limit, min_id, max_id channels.getMessages: Fetch specific messages by ID Useful for targeted retrieval of known message IDs Admin Post Identification: For signed posts: Check message.post_author For supergroups: Use ChannelParticipantsAdmins filter Match message sender against admin list Bot API Limitation: ❗ Important: Bot API cannot retrieve historical messages Bots only receive new messages posted after they join as admin MTProto PAGINATION FLOW messages.getHistory Returns up to 100 messages per request offset_id limit max_id min_id Parameters control pagination through message history  Increment offset_id for next page TELETHON IMPLEMENTATION Efficient Pagination with Telethon # Simplest approach - automatic pagination async for message in client.iter_messages( channel, reverse=True, # Oldest first limit=None # All messages ): process_message(message) Manual Pagination Control For advanced cases when you need more control: Save last_id between runs for incremental updates Implement offset + limit pattern for batching Handle FloodWaitError exceptions gracefully 4
5. REAL-TIME MONITORING METHODS Monitoring Approaches: Two primary API families provide different methods for real-time capture of new Telegram channel posts Key Monitoring Options: Bot API: HTTP-based with long polling or webhooks MTProto Client API: Event-driven subscription model Bot API requires admin permissions for channel_post updates MTProto works with regular user accounts or bots Reliability Considerations: Persist update_id/message_id to resume after interruptions Implement exponential backoff for rate limit handling Ensure idempotent processing to prevent duplicates Monitor connection health and reconnect automatically MONITORING APPROACHES DIAGRAM  Long Polling getUpdates with timeout Client repeatedly requests  Webhooks setWebhook Server pushes to your endpoint  Event Subscription NewMessage events Telethon/Pyrogram callbacks  Update Handling Process update objects Extract channel_post data IMPLEMENTATION DETAILS Bot API Long Polling: getUpdates(offset=last_id+1, timeout=30, allowed_updates= ["channel_post"]) Bot API Webhook: setWebhook(url="https://your-domain.com/hook", allowed_updates=["channel_post"]) MTProto Events: @client.on(events.NewMessage(chats=[channel_id])) async def handler(event) 5
6. TELETHON VS PYROGRAM VS BOT API Implementation Options: Choosing the right API approach based on your use case requirements Key Considerations: Do you need historical data retrieval? Authentication complexity you can manage How you'll host the solution (server, serverless) Technical sophistication of your team Selection Guide: Need complete channel history? → Choose MTProto (Telethon/Pyrogram) Need simple HTTP API? → Choose Bot API Need admin rights? → All options require admin for channel posts Robust user data & events? → Telethon offers richest object model API COMPARISON  Telethon (MTProto) Pros:  Full message history access  Rich object models & events  Powerful async iterators Cons:  Requires user login & session  Handle FLOOD_WAIT errors  More complex authentication  Pyrogram (MTProto) Pros:  Modern, elegant API design  Full message history access  Supports both user & bot modes Cons:  Auth/session complexity  Rate limiting concerns  Requires user phone verification  Bot API (HTTP) Pros:  Simple HTTP requests  Easy webhooks/long polling  Simple token authentication Cons:  No historical data access  Must be admin to get updates  Limited to real-time updates 6
7. TELETHON CODE EXAMPLES Telethon Implementation: Ready-to-use code snippets for fetching and monitoring Telegram Channel posts using the Telethon library. These examples demonstrate: Full historical backfill of channel posts Real-time monitoring with event handlers Working with both public and private channels Implementation Notes: Error handling omitted for brevity Store the last processed message ID for resumability Always implement exponential backoff for FLOOD_WAIT errors Consider using async with threading for production use TELETHON CODE SNIPPETS Historical Backfill from telethon import TelegramClient, utils from telethon.tl.functions.messages import ImportChatInviteRequest # Authentication client = TelegramClient('session_name', api_id, api_hash) await client.start() # Join private channel if needed try: invite_hash = 'DKcwQbX3QRphMjFk' # From t.me/+DKcwQbX3QRphMjFk await client(ImportChatInviteRequest(invite_hash)) except: pass # Already in channel # Backfill all messages (oldest first) async for message in client.iter_messages('t.me/+DKcwQbX3QRphMjFk', Real-time Monitoring from telethon import TelegramClient, events client = TelegramClient('session_name', api_id, api_hash) # Register event handler for new messages @client.on(events.NewMessage(chats=['t.me/+DKcwQbX3QRphMjFk'])) async def new_message_handler(event): message = event.message # Process new channel post print(f"New post {message.id}: {message.text}") save_to_database(message.id, message.date, message.text) @client.on(events.MessageEdited(chats=['t.me/+DKcwQbX3QRphMjFk'])) async def edited_message_handler(event): # Handle edits to existing posts 7
8. BOT API CODE IMPLEMENTATION Webhook Setup: Configure your bot to receive updates via HTTPS callbacks # Set up webhook using requests library import requests TOKEN = "123456:ABC-DEF1234ghIkl-zyx57W2v1u123ew11" WEBHOOK_URL = "https://your-domain.com/webhook" api_url = f"https://api.telegram.org/bot{TOKEN}/setWebhook" params = { "url": WEBHOOK_URL, "allowed_updates": ["channel_post"], } response = requests.post(api_url, json=params) print(response.json()) Benefits of Webhook Approach: Immediate update delivery (no polling delay) More efficient than long polling for high-traffic bots Can be deployed on serverless platforms WEBHOOK HANDLER EXAMPLE # Flask webhook handler example from flask import Flask, request, jsonify import json app = Flask(__name__) BOT_TOKEN = "123456:ABC-DEF1234ghIkl-zyx57W2v1u123ew11" @app.route(f"/webhook", methods=['POST']) def webhook_handler(): # Parse incoming update update = request.get_json() # Check if update contains channel post if 'channel_post' in update: channel_post = update['channel_post'] chat_id = channel_post['chat']['id'] message_id = channel_post['message_id'] message_text = channel_post.get('text', "") # Process channel post process_channel_post(chat_id, message_id, message_text) return jsonify({'ok': True}) def process_channel_post(chat_id, message_id, text): # Your processing logic here print(f"New post in {chat_id}: {text[:30]}...") # Save to database, trigger notifications, etc. Deployment: Host on HTTPS-enabled server (Cloudflare Workers, Vercel, etc.) Security: Optionally add secret_token parameter to setWebhook for request validation 8
9. N8N INTEGRATION WITH TELEGRAM What is n8n: A visual workflow automation platform that can connect to Telegram for no-code/low-code channel monitoring and data processing Setup Steps: Create a Telegram bot via @BotFather and obtain API token Add the bot as admin to your target channel Configure n8n Telegram Trigger node with your bot token Select "Channel Post" event for monitoring new posts Practical Use Cases: Automated content archiving to databases (PostgreSQL, MongoDB) Cross-posting between Telegram and other platforms (Twitter, Discord) Content analysis with AI integration (OpenAI, sentiment analysis) Real-time alerting based on keyword triggers or post patterns VISUAL WORKFLOW DIAGRAM IMPLEMENTATION EXAMPLES Content Archive: Telegram Trigger → HTTP Request (fetch media) → PostgreSQL Cross-platform Posting: Telegram Trigger → Filter (has media) → Twitter/Discord Alert System: Telegram Trigger → Function (keyword match) → Send Email/SMS  Telegram Trigger Event: Channel Post   Filter / Process IF, Switch, Function nodes   Database  Notifications  API Calls 9
10. RATE LIMITS & BEST PRACTICES Bot API Limitations: Key constraints to consider when building your data collection workflow. Global Rate: ~30 requests per second maximum Channel Posts: ~20 messages per minute for groups/channels Update Retention: Updates stored for max 24 hours MTProto Considerations: Handle FLOOD_WAIT_X errors with exponential backoff Use reasonable page sizes (100-200 messages) Initialize with session file to avoid repeated logins Account for timezone differences in message timestamps API RATE COMPARISON IMPLEMENTATION BEST PRACTICES DATA PIPELINE Store message_id, date, text, media refs Deduplicate on (chat_id, message_id) Support incremental resume from last_id RELIABILITY Recalculate offset after each response Persist state for failure recovery Implement retry mechanisms COMPLIANCE Respect channel privacy settings Avoid scraping private channels without permission Consider data protection regulations OPTIMIZATION Use webhooks for real-time efficiency Implement caching where appropriate Batch operations when possible Bot API (Global) 30 req/sec Bot API (Channels) 20 msg/min MTProto Varies (with FLOOD_WAIT) 8
11. CONCLUSION & RESOURCES Key Takeaways: API Choice: Use MTProto for full history retrieval; Bot API for simpler real- time monitoring on admin channels Data Pipeline: Plan for pagination, offsets, and retries to handle large datasets Reliability: Persist state between runs for resumable operations and crash recovery Implementation Strategy: Start with a test channel to familiarize yourself with rate limits Implement error handling for FLOOD_WAIT errors and API exceptions Design a storage strategy for messages and media content Consider privacy and terms of service when scraping channel data OFFICIAL DOCUMENTATION  MTProto API References Core Telegram API methods for historical data retrieval messages.getHistory: https://core.telegram.org/method/messages.getHistory channels.getMessages: https://core.telegram.org/method/channels.getMessages  Bot API Documentation HTTP-based interface for real-time monitoring Bot API: https://core.telegram.org/bots/api getUpdates & Webhooks: https://core.telegram.org/bots/api#getting-updates  Python Client Libraries High-level wrappers for Telegram APIs Telethon: https://docs.telethon.dev Pyrogram: https://docs.pyrogram.org  Example Channel Channel used for demonstration in this presentation https://t.me/+DKcwQbX3QRphMjFk 9