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What Are User Properties?

User properties are attributes about your users, like their subscription plan, location, or preferences. They help you:
  • Segment users: Group users by plan, location, behavior
  • Personalize experiences: Show different content based on properties
  • Analyze behavior: Compare how different user groups behave
Think of properties as tags or labels that describe a user beyond just their ID.

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Setting Properties

Use setProperty() to add attributes to a user: 
await grain.setProperty({
  plan: 'premium',
  location: 'US',
  signup_date: '2024-01-15'
});
Key points:
  • Set up to 4 properties per request
  • All values are automatically converted to strings
  • Properties persist for the user
  • Works with the current user ID (from setUserId())

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Property Values

All property values become strings, regardless of what you pass: 
await grain.setProperty({
  plan: 'premium',        // String: "premium"
  age: 25,               // Becomes: "25"
  is_active: true,       // Becomes: "true"
  preferences: {         // Becomes: JSON string
    theme: 'dark',
    language: 'en'
  }
});
Why strings? This keeps the API simple and ensures consistent storage. When checking properties, compare as strings.

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When to Set Properties

Set properties when they change or when a user first signs up: 
// After signup
grain.setUserId('user_123');
await grain.setProperty({
  plan: 'free',
  signup_date: new Date().toISOString(),
  source: 'landing_page'
});

// When user upgrades
await grain.setProperty({
  plan: 'premium',
  upgrade_date: new Date().toISOString()
});

// When preferences change
await grain.setProperty({
  theme: 'dark',
  language: 'es'
});

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Setting for Specific Users

Override which user receives properties using options: 
// Set properties for a different user
await grain.setProperty({
  status: 'inactive'
}, { userId: 'user_456' });
Security: Only use userId overrides when you have permission to modify other users. With JWT auth, the user ID must match your token. Learn more in Security.

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Properties for Personalization

Properties power remote configuration personalization. When fetching configs, pass properties to get personalized values: 
// User properties influence which config values are returned
const heroText = await grain.getConfigAsync('hero_text', {
  properties: {
    plan: 'premium',
    location: 'US'
  }
});
For example, premium users might see “Welcome back, premium member!” while free users see “Upgrade to premium!”. This is covered in depth in Remote Configuration and Personalization Guide.

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Common Properties

Here are properties commonly tracked in applications:

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Account Properties

await grain.setProperty({
  plan: 'premium',
  status: 'active',
  trial_end: '2024-12-31'
});

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Demographic Properties

await grain.setProperty({
  location: 'US',
  language: 'en',
  timezone: 'America/New_York'
});

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Behavioral Properties

await grain.setProperty({
  last_login: new Date().toISOString(),
  feature_usage_count: '42',
  onboarding_completed: 'true'
});

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Property Limits

To prevent abuse and ensure performance:
  • 4 properties per request maximum
  • Rate limiting may apply if setting properties too frequently
  • Property keys and values have size limits (typically 256 chars)
If you need to set more than 4 properties: 
// Set in batches
await grain.setProperty({
  plan: 'premium',
  status: 'active',
  location: 'US',
  language: 'en'
});

await grain.setProperty({
  theme: 'dark',
  notifications: 'enabled',
  last_login: new Date().toISOString()
});

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Security Considerations

User properties have security restrictions to prevent abuse:

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User ID Must Match JWT

With JWT authentication, you can only set properties for the authenticated user: 
// JWT subject: "user_123"

// ✅ Allowed: Setting properties for yourself
grain.setUserId('user_123');
await grain.setProperty({ plan: 'premium' });

// ❌ Blocked: Can't set properties for other users
await grain.setProperty({ 
  plan: 'premium' 
}, { userId: 'user_456' });

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Rate Limiting

Setting properties for many different user IDs from the same source may trigger rate limiting. This prevents one client from modifying many user profiles. Learn more in Security.

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Async Operations

setProperty() is asynchronous - it returns a Promise: 
// Wait for completion
await grain.setProperty({ plan: 'premium' });

// Or handle with .then()
grain.setProperty({ status: 'active' })
  .then(() => console.log('Properties set!'))
  .catch(err => console.error('Failed:', err));
Error handling: 
try {
  await grain.setProperty({ plan: 'premium' });
} catch (error) {
  console.error('Failed to set properties:', error);
  // Show user an error message
}

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React Integration

With React hooks, manage properties easily: 
import { useGrainAnalytics } from '@grainql/analytics-web/react';

function SettingsPage() {
  const grain = useGrainAnalytics();
  
  const handleThemeChange = async (theme) => {
    await grain.setProperty({ theme });
    // UI updates...
  };
  
  return <button onClick={() => handleThemeChange('dark')}>Dark Mode</button>;
}

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Next Steps

Remote Configuration

Use properties for personalization

Personalization Guide

Build personalized experiences

Security

Understand security restrictions