Setting a User ID

Send your internal user ID to Singular to enable cross-device tracking and user-level data reporting.

User ID Requirements

Privacy and Best Practices

Follow these guidelines when implementing user ID tracking to ensure privacy compliance and proper cross-device measurement.

• No PII: The User ID should not expose Personally Identifiable Information (PII) such as email addresses, usernames, or phone numbers. Use a hashed value unique to your first-party data.
• Consistency Across Platforms: The User ID value must be the same internal identifier you capture across all platforms (Web/Mobile/PC/Console/Offline) for accurate cross-device measurement.
• First-Party Data: Singular includes the User ID in user-level exports, ETL, and Internal BI postbacks (if configured). The User ID is first-party data and is not shared with third parties.
• Persistence: The User ID persists until explicitly unset using unsetCustomUserId() or until the app is uninstalled. Closing or restarting the app does not clear the User ID.

Implementation Overview

When to Set the User ID

Use Singular.setCustomUserId() to set the user identifier and Singular.unsetCustomUserId() to clear it during logout.

If you already know the user ID when the app opens, configure it using the customUserId property before initializing the Singular SDK. This ensures Singular receives the User ID from the first session. However, the User ID is typically unavailable until the user registers or logs in, in which case call setCustomUserId() after the registration or authentication flow completes.

SDK Methods

Set Custom User ID

Send your internal user ID to Singular for cross-device tracking and user-level reporting.

import 'package:singular_flutter_sdk/singular.dart';

// Set the user ID after login or registration
Singular.setCustomUserId('user_123456');

Method Signature:

static void setCustomUserId(String customUserId)

Example: Set User ID After Login

Call setCustomUserId() immediately after the user successfully completes authentication to ensure all subsequent events are associated with their user ID.

import 'package:singular_flutter_sdk/singular.dart';

Future<void> handleUserLogin(String email, String password) async {
  try {
    // Your authentication logic
    final response = await authenticateUser(email, password);

    if (response.success) {
      // Set the user ID in Singular after successful login
      Singular.setCustomUserId(response.userId);

      print('User ID set: ${response.userId}');

      // Navigate to home screen
      navigateToHome();
    }
  } catch (error) {
    print('Login failed: $error');
  }
}

Unset Custom User ID

Clear the user ID when a user logs out to ensure accurate session tracking for multi-user devices.

import 'package:singular_flutter_sdk/singular.dart';

// Unset the user ID on logout
Singular.unsetCustomUserId();

Method Signature:

static void unsetCustomUserId()

Example: Unset User ID on Logout

Call unsetCustomUserId() during the logout flow to clear the user ID and prevent incorrect attribution of subsequent events.

import 'package:singular_flutter_sdk/singular.dart';

Future<void> handleUserLogout() async {
  try {
    // Clear app data and user session
    await clearUserSession();

    // Unset the user ID in Singular
    Singular.unsetCustomUserId();

    print('User ID cleared');

    // Navigate to login screen
    navigateToLogin();
  } catch (error) {
    print('Logout failed: $error');
  }
}

Set User ID During Initialization

If the user ID is available when the app launches (e.g., user is already logged in), configure it during SDK initialization using the customUserId property. This ensures the first session includes the user ID.

import 'package:flutter/material.dart';
import 'package:singular_flutter_sdk/singular.dart';
import 'package:singular_flutter_sdk/singular_config.dart';
import 'package:shared_preferences/shared_preferences.dart';

void main() {
  runApp(MyApp());
}

class MyApp extends StatefulWidget {
  @override
  _MyAppState createState() => _MyAppState();
}

class _MyAppState extends State<MyApp> {
  @override
  void initState() {
    super.initState();
    initializeSingular();
  }

  Future<void> initializeSingular() async {
    // Check if user is already logged in
    final prefs = await SharedPreferences.getInstance();
    final userId = prefs.getString('user_id');

    // Create configuration
    SingularConfig config = SingularConfig(
      'YOUR_SDK_KEY',
      'YOUR_SDK_SECRET'
    );

    // If user ID exists, set it during initialization
    if (userId != null) {
      config.customUserId = userId;
    }

    // Initialize SDK
    Singular.start(config);
  }

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      home: MyHomePage(),
    );
  }
}

Configuration Property:

String? customUserId