How to Send User Metadata Along with Prompts to Gemini from n8n

1// Expected payload:
2// POST /webhook/gemini-personalized
3// {
4//   "message": "When is my subscription renewing?",
5//   "userId": "user_42",
6//   "userName": "Sarah Chen",
7//   "email": "sarah@example.com",
8//   "timezone": "America/New_York",
9//   "plan": "pro",
10//   "locale": "en-US",
11//   "signupDate": "2025-06-15"
12// }

1// PostgreSQL node query:
2// SELECT name, email, plan, timezone, locale, signup_date, 
3//        interaction_count, last_active_at
4// FROM users 
5// WHERE id = '{{ $json.userId }}'

1const webhook = $input.first().json;
2
3// Merge webhook data with database data if available
4const dbData = $('PostgreSQL').first()?.json || {};
5
6const user = {
7  name: webhook.userName || dbData.name || 'User',
8  plan: webhook.plan || dbData.plan || 'free',
9  timezone: webhook.timezone || dbData.timezone || 'UTC',
10  locale: webhook.locale || dbData.locale || 'en-US',
11  signupDate: webhook.signupDate || dbData.signup_date || 'unknown',
12  interactionCount: dbData.interaction_count || 0,
13  lastActive: dbData.last_active_at || 'unknown'
14};
15
16// Build structured context block
17const contextBlock = [
18  '--- USER CONTEXT ---',
19  `Name: ${user.name}`,
20  `Plan: ${user.plan}`,
21  `Timezone: ${user.timezone}`,
22  `Locale: ${user.locale}`,
23  `Member since: ${user.signupDate}`,
24  `Total interactions: ${user.interactionCount}`,
25  `Last active: ${user.lastActive}`,
26  '--- END USER CONTEXT ---'
27].join('\n');
28
29return [{
30  json: {
31    message: webhook.message,
32    userId: webhook.userId,
33    userContext: contextBlock,
34    userData: user
35  }
36}];

1// System Message expression for the Gemini node:
2// You are a helpful support assistant for AcmeApp.
3//
4// {{ $json.userContext }}
5//
6// INSTRUCTIONS:
7// - Address the user by their name when appropriate.
8// - When mentioning times or dates, use the user's timezone.
9// - Tailor feature recommendations to the user's plan (free/pro/enterprise).
10// - For free plan users, mention relevant pro features when naturally appropriate.
11// - Use the user's locale for number and date formatting.
12// - Never reveal the raw user context block to the user.

1// In the Code node, always fetch fresh data:
2const dbData = $('PostgreSQL').first()?.json || {};
3
4// Don't cache user metadata in the session — always re-query
5// This ensures plan changes, timezone updates, etc. are reflected immediately