Create a virtual outfit try-on Telegram bot with async polling and Google Sheets

Description

👗 Virtual Try-On Telegram Bot — AI Outfit Try-On via Telegram with Async Job Polling

Try on any outfit virtually - right inside Telegram. A user sends a person photo, then a garment photo (captioned garment), and the bot replies with an AI-generated try-on result image using a dedicated Virtual Try-On API. No app. No frontend. Just a Telegram chat.

🎯 Who Is This For?

Fashion e-commerce brands** wanting to offer a try-before-you-buy experience via a simple chat interface
Telegram bot developers** looking for a real-world async API polling pattern with state management
AI product builders** who want a plug-and-play virtual fitting room for their audience
Boutiques & clothing stores** wanting to let customers preview outfits before ordering

⚙️ What This Workflow Does

Receives a Telegram message and checks if it contains a photo
Person photo (sent without caption) → saves chat_id + file_id to Google Sheets as session state
Garment photo (sent with caption garment) → looks up the saved person photo, resolves both Telegram file URLs, downloads both images, and submits a try-on job to the API
Async polling loop → waits 15 seconds, checks job status, loops until completed or failed
Sends the result back to the user as a photo in Telegram, then cleans up the sheet row

🔑 Credentials & APIs Required

| Service | Purpose | Where to Get It |
|---|---|---|
| Telegram Bot Token | Receive messages & send results | Create a bot via @BotFather on Telegram → /newbot |
| Virtual Try-On API Key | Submit and poll try-on jobs | Sign up at your Try-On API provider (e.g. try-on api or your own deployment) |
| Google Sheets OAuth2 | Store per-user session state between messages | Connect via n8n's built-in Google Sheets OAuth2 credential |

> 💡 Why Google Sheets for state? Each Telegram message triggers a separate workflow execution - there's no shared memory between runs. Google Sheets acts as a lightweight session store using chat_id as the unique key.

🛠️ Setup Instructions

Step 1 - Telegram Bot
Open Telegram and message @BotFather
Run /newbot, follow the prompts, copy your Bot Token
Paste the token into the ⚙️ Config node under botToken

Step 2 - Google Sheet
Create a new Google Sheet
Add a tab named exactly tryon-state
Add two column headers in row 1: chat_id and person_file_id
Copy the Sheet ID from the URL (docs.google.com/spreadsheets/d/{THIS_PART}/edit)
Paste it into the ⚙️ Config node under sheetId

Step 3 - Try-On API
Obtain your API key from your Virtual Try-On provider
Set tryonApiKey in the ⚙️ Config node
If your API base URL differs, also update tryonApiBase
Verify the API accepts POST /api/v1/tryon with multipart/form-data fields person_images and garment_images, and returns { jobId, statusUrl } - adjust the Submit Try-On Job and Check Job Status nodes if your provider's schema differs

Step 4 - n8n Credentials
Assign your Telegram credential to all Telegram nodes (Trigger + all send nodes)
Assign your Google Sheets OAuth2 credential to all Google Sheets nodes
Activate** the workflow - the Telegram Trigger only works when the workflow is active

🔄 How the Polling Loop Works

The Try-On API is asynchronous - submitting a job returns a jobId, not the result immediately. The workflow:

Submits the job → gets jobId
Waits 15 seconds
Calls the status endpoint: GET /api/v1/tryon/status/{jobId}
If status === "completed" → downloads and sends the result image
If status === "failed" → sends an error message to the user
Otherwise → loops back to the wait step

Typical total wait: 15–60 seconds depending on the API and queue load.

🎨 How to Customize

Change the garment trigger keyword* → Edit the caption check in *Is Garment Photo?** node from garment to anything you like (e.g. outfit, try, wear)
Add a category/garment type input** → Extend the caption parsing to accept values like top, dress, jacket and pass them as an extra field to your Try-On API if supported
Use a different state store* → Swap Google Sheets for Airtable, Supabase, or Redis if you have higher traffic needs; just replace the *Save Person to Sheet* and *Lookup Person from Sheet** nodes
Add a paid/subscription gate** → Before saving the person photo, check a users sheet or database to see if the chat_id has remaining credits
Support multiple garments in one session** → Instead of deleting the person row after each try-on, keep it for 24 hours so users can try multiple garments without re-uploading the person photo
Add a result watermark* → Insert an n8n Code node after *HTTP Request** (result download) to overlay your brand logo before sending

📋 Workflow Nodes Overview

| Node | Role |
|---|---|
| Telegram Trigger | Listens for incoming messages |
| Extract Message Info | Pulls out chat_id, caption, hasPhoto, fileId |
| ⚙️ Config | Single place for all configurable values — edit this first |
| Has Photo? | Routes messages that contain a photo |
| Is Garment Photo? | Checks if caption equals garment |
| Save Person to Sheet | Stores person file_id keyed by chat_id |
| Lookup Person from Sheet | Retrieves saved person photo when garment arrives |
| Has Person Saved? | Guards against out-of-order photos |
| Collect IDs | Bundles all required IDs for downstream nodes |
| Get Person/Garment File Path | Resolves Telegram file_id → file_path via getFile API |
| Download Person/Garment Image | Downloads actual image binary from Telegram CDN |
| Submit Try-On Job | POSTs both images to the Try-On API |
| Wait 15 Seconds | Gives the API time before first status check |
| Check Job Status | Polls job status endpoint |
| Is Job Complete? / Is Job Failed? | Routes to success or error path |
| HTTP Request (result download) | Downloads the result image as binary |
| Send Result Photo | Sends the AI try-on image back to the user |
| Delete Row from Sheet | Cleans up session state after successful result |

⚠️ Notes & Gotchas

Telegram file URLs expire** - the workflow resolves and downloads images immediately; never store Telegram download URLs for later use
The bot must be activated** for the Telegram webhook to register - n8n does not receive messages while the workflow is inactive
Google Sheets appendOrUpdate** uses chat_id as the matching key, so a user can retake their person photo any time and it will overwrite the old entry
Pinned test data** is included in Submit Try-On Job and Merge State nodes for local testing — remove or disable these pins before going live

🔗 Useful Links

Telegram BotFather — Create your bot
n8n Telegram node docs
n8n Google Sheets node docs
n8n HTTP Request node docs
n8n Wait node docs
n8n Community Forum