userId and deviceId in Configuration are ignored

[jerelevine]

Expected Behavior

When passing userId and deviceId in the Configuration object during Amplitude initialization, the SDK should use the provided values instead of generating its own.

Current Behavior

Both the userId and deviceId parameters in the Configuration object are completely ignored by both iOS and Android native implementations. The SDK generates its own device ID during initialization, and when getUserId() and getDeviceId() are called later, they return auto-generated/null values instead of the ones provided in the configuration.

Possible Solution

The native iOS and Android plugins need to handle both userId and deviceId parameters in their getConfiguration methods:

iOS (SwiftAmplitudeFlutterPlugin.swift):
Add these to the getConfiguration method around line 221:

if let userId = args["userId"] as? String {
    configuration.userId = userId
}
if let deviceId = args["deviceId"] as? String {
    configuration.deviceId = deviceId
}

Android (AmplitudeFlutterPlugin.kt):
Add these to the getConfiguration method around line 226:

call.argument<String>("userId")?.let { configuration.userId = it }
call.argument<String>("deviceId")?.let { configuration.deviceId = it }

Steps to Reproduce

1. Create a Configuration object with custom userId and deviceId:

final config = Configuration(
  apiKey: 'your-api-key',
  userId: 'custom-user-123',
  deviceId: 'custom-device-id-456',
);

2. Initialize Amplitude with this configuration:

final amplitude = Amplitude(config);
await amplitude.isBuilt;

3. Retrieve the user ID and device ID:

final userId = await amplitude.getUserId();
final deviceId = await amplitude.getDeviceId();
print('User ID: $userId'); // This will NOT be 'custom-user-123'
print('Device ID: $deviceId'); // This will NOT be 'custom-device-id-456'

4. Both returned values will be auto-generated/null instead of the custom ones provided in the configuration.

Environment

• SDK Version: amplitude_flutter 4.3.7

Additional Notes

• Both setUserId() and setDeviceId() methods work correctly when called after initialization
• Both userId and deviceId parameters are included in the Configuration.toMap() output but ignored by native plugins
• This affects both iOS and Android platforms
• Workaround: Use setUserId() and setDeviceId() after initialization instead of passing them in Configuration

[chungdaniel]

Hi @jerelevine, thanks for bringing this issue up! So our Flutter SDK is built on our native Amplitude-Swift, Amplitude-Kotlin, and Amplitude-Typescript SDKs, as you may have noticed.

For iOS, we don't actually support passing in userId or deviceId, so this is expected. You'll need to call the set methods as needed (but once they're set, the SDK should store this information and subsequent startups do not require these calls).

For Android, we only support deviceId being passed in as part of the Configuration object. You are correct that we currently ignore this! I have created a fix for this in

For web, both userId and deviceId being respected in configuration are supported.

You can see in our docs (both in code and on our website) which platforms support which configurations.

[github-actions]

🎉 This issue has been resolved in version 4.3.8 🎉

The release is available on GitHub release

Your semantic-release bot 📦🚀

[jerelevine]

Hi @jerelevine, thanks for bringing this issue up! So our Flutter SDK is built on our native Amplitude-Swift, Amplitude-Kotlin, and Amplitude-Typescript SDKs, as you may have noticed.

For iOS, we don't actually support passing in userId or deviceId, so this is expected. You'll need to call the set methods as needed (but once they're set, the SDK should store this information and subsequent startups do not require these calls).

For Android, we only support deviceId being passed in as part of the Configuration object. You are correct that we currently ignore this! I have created a fix for this in

For web, both userId and deviceId being respected in configuration are supported.

You can see in our docs (both in code and on our website) which platforms support which configurations.

That’s a unfortunate - having iOS ignore userId and deviceId in configuration while Android (and Web) respect them means we’ll end up with inconsistent initialization behavior across platforms.

[chungdaniel]

@jerelevine I hear you. Will look into this, but in the meantime, to keep things consistent, you could hold off on passing userId and deviceId in the configuration and use the setUserId() and setDeviceId() methods you mentioned above for all platforms.