---
title: "User identification"
slug: "user-identification-flutter-engage"
updated: 2026-04-17T09:17:20Z
published: 2026-04-17T09:17:20Z
canonical: "docs.mapp.com/user-identification-flutter-engage"
---

> ## Documentation Index
> Fetch the complete documentation index at: https://docs.mapp.com/llms.txt
> Use this file to discover all available pages before exploring further.

# User identification

The Mapp Engage Flutter plugin supports a device-first identification model. After initialization, each device starts with an anonymous AUTO alias. When a user signs in, you can replace that alias with a known identifier to associate the device with a Mapp contact.

This guide explains how to identify users, when to update aliases, and how to handle logout correctly.

## How user identification works

When the SDK is initialized, the device is registered with an anonymous AUTO alias. This alias allows the SDK to operate before the user is known.

Once the user signs in, call `setAlias()` to replace the AUTO alias with a known identifier such as an email address or customer ID.

After that, the device is associated with the resolved contact and future engagement data is linked to that identity.

---

## Get the current alias

Use `getAlias()` to retrieve the alias currently assigned to the device.

```dart
final String alias = await MappSdk.getAlias();
print('Current alias: $alias');
```

Before login, this usually returns the AUTO alias. After login, it returns the alias you assigned with `setAlias()`.

---

## Set a known alias after login

Call `setAlias()` after a successful login or after your application can reliably identify the user.

```dart
await MappSdk.setAlias('user@example.com');
```

When you set a known alias:

- The AUTO alias is replaced
- The device is associated with the supplied identifier
- The SDK can attach the device to an existing Mapp contact or create a new one

Use an identifier that is stable and unique for the user in your system.

---

## When to call setAlias()

The correct moment to call `setAlias()` is after user authentication has completed successfully.

A typical flow looks like this:

1. Initialize the SDK on app launch
2. Let the device operate with its AUTO alias
3. Authenticate the user in your application
4. Call `setAlias()` with the resolved user identifier

Do not call `setAlias()` before the app can reliably identify the user.

---

## Resend custom attributes after alias changes

If your app stores custom attributes before the user signs in, you can use `setAliasWithResend()` to re-send those attributes after the alias is updated.

```dart
await MappSdk.setAliasWithResend('user@example.com', true);
```

The second argument controls whether previously stored custom attributes are sent again after the alias change.

| Parameter | Type | Description |
| --- | --- | --- |
| `alias` | `String` | The user identifier to assign to the device. |
| `resendCustomAttributes` | `bool` | If set to `true`, previously stored custom attributes are sent again after the alias update. |

This is useful when attributes were collected while the device was still anonymous and should also be associated with the resolved contact.

---

## Handle logout correctly

Use `logOut()` when the user signs out of your application.

```dart
await MappSdk.logOut(false);
```

The method accepts a positional boolean argument.

| Argument | Type | Description |
| --- | --- | --- |
| `pushEnabled` | `bool` | Controls whether push notifications remain enabled after logout. |

When logout is completed:

- The user alias is removed
- The device is detached from the identified contact
- A new AUTO alias is assigned
- Push behavior follows the `pushEnabled` argument

---

## Do not use an empty alias to reset identity

Do not pass an empty string to `setAlias()` to return the device to anonymous state.

Use `logOut()` instead. This ensures that the SDK resets the identification state correctly and restores a new AUTO alias for the device.

---

## Recommended identification flow

1. Initialize the SDK on app start
2. Allow the device to register with its AUTO alias
3. Set a known alias after login
4. Update tags and custom attributes as needed for the identified contact
5. Call `logOut()` when the user signs out

This approach keeps anonymous and identified states clearly separated and supports a predictable engagement lifecycle.

---

## Common mistakes

- Calling `setAlias()` before the user is authenticated
- Using `setAlias()` with an empty value to simulate logout
- Forgetting to call `logOut()` on sign-out
- Using a non-unique alias value
- Skipping `setAliasWithResend()` when previously stored custom attributes should be associated with the identified contact

---

## Best practices

- Use a stable and unique identifier for aliases
- Call `setAlias()` only after successful authentication
- Use `setAliasWithResend()` when anonymous custom attributes should be preserved for the identified contact
- Always use `logOut()` to return to anonymous state
- Keep your app's login and logout flow aligned with the SDK identification lifecycle