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Using Transient Traits and Identities

Overview​

By the end of this tutorial, you'll be able to use transient traits and identities in Flagsmith to evaluate feature flags for anonymous or privacy-sensitive users, without storing their data.

Prerequisites:

  • A Flagsmith project and environment set up
  • Basic knowledge of feature flags and traits
  • Access to a Flagsmith SDK (e.g., JavaScript)

Background​

Transient traits and identities allow you to evaluate feature flags for users without persisting their data. This is useful for privacy, compliance, and temporary/anonymous user scenarios.

Before You Begin​

  • Ensure you have a Flagsmith account and project.
  • Install the Flagsmith SDK for your platform (e.g., npm install flagsmith for JavaScript).
  • Obtain your environment key from the Flagsmith dashboard.

Steps​

1. Initialize the SDK​

import flagsmith from 'flagsmith';

flagsmith.init({
  environmentID: 'YOUR_ENVIRONMENT_KEY',
});

2. Evaluate a Feature Flag with a Transient Trait​

Suppose you want to target users based on their email domain, but don’t want to store their email.

flagsmith.updateContext({
  identity: {
    identifier: 'user-123',
    traits: {
      email: { value: 'alice@example.com', transient: true },
    },
  },
});

The flag evaluation will use the email trait, but Flagsmith will not store it.

3. Evaluate a Feature Flag for an Anonymous User​

You can use a transient identity for a guest or temporary session:

flagsmith.init({
  evaluationContext: {
    identity: {
      identifier: null,
      traits: {
        sessionStartTime: { value: Date.now(), transient: true },
      },
    },
  },
});

Flags are evaluated for this session, but no identity or trait is stored.

4. Combine Multiple Transient Traits​

You can send several transient traits for complex targeting:

flagsmith.updateContext({
  identity: {
    identifier: 'visitor-456',
    traits: {
      location: { value: 'US', transient: true },
      cartValue: { value: 299.99, transient: true },
      pageViews: { value: 5, transient: true },
    },
  },
});

Summary​

You’ve learned how to:

  • Use transient traits to evaluate feature flags without storing sensitive data
  • Target anonymous or temporary users with transient identities
  • Combine multiple transient traits for advanced targeting

Next Steps​

  • Explore Flagsmith SDK documentation
  • Try using transient traits in your own app
  • Review your privacy requirements and update your flag targeting accordingly
tip

Consider using transient traits for:

  • User location data
  • Session information
  • Temporary preferences
  • Testing scenarios
important

Transient traits are evaluated in real-time and cannot be used for historical analysis since they are not stored.