LINE + Gemini Clean Plate Reward Bot with n8n & Google Sheets

Turn Daily “Clean Your Plate” Into a Reward Streak—Automated with LINE, Google Gemini, n8n & Google Sheets

The LINE + Gemini Clean Plate Reward Bot with n8n & Google Sheets automatically scores your child’s meal photo, generates an encouraging message, and tracks stamps + consecutive-day streaks in Google Sheets—powered end-to-end by an n8n webhook.

What this workflow does

• Receives LINE messages via a POST webhook from your LINE bot when a user interacts with the bot.
• Validates message type: if the incoming LINE message is not an image, it replies with clear instructions.
• Downloads the image from the LINE Messaging API so it can be analyzed.
• Sends the photo to Google Gemini to judge whether it shows a plate, then:
  • calculates a score for how much was eaten
  • creates a short praise message
• Computes today’s stamps + streak by reading prior entries from a Google Sheets “Log” tab and building a stamp-card message.
• Writes the result back to Google Sheets, appending: date/time, score, leftovers, stamps earned, and the comment—then sends the final message back to the child in LINE.

Use cases

• Parents want a fun, consistent “clean plate” reward system without manual tracking.
• n8n users/automation engineers need a practical example of LINE webhook handling + AI scoring + Google Sheets logging.
• SaaS operators building lightweight family or education bots that rely on Google Gemini and structured spreadsheet storage.

Technical details

• LINE Messaging API webhook receiver (POST webhook) and image handling
• Google Gemini (PaLM) integration to score plate cleanliness and generate praise
• Google Sheets OAuth2 integration (uses a “Log” tab with columns: Date, Time, Child Name, Clean Plate, Score, Leftovers, Stamps Earned, Comment)
• n8n nodes used: if, set, code, webhook, sticky note, http request

Get set up by creating a LINE Messaging API channel (enable webhooks, add the Channel access token), adding Gemini and Google Sheets credentials to n8n, creating the “Log” tab sheet, and pasting the n8n webhook URL into the LINE Developers configuration.