Authenticate Users - Flutter SDK
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Atlas App Services provides an API for authenticating users using any enabled
authentication provider. Instantiate a Credentials
object and pass it to App.logIn()
to authenticate and create a User
object for that user.
Each authentication provider corresponds to a static constructor method
used to instantiate Credentials objects for that authentication provider.
Before You Begin
Enable and configure one or more App Services authentication providers.
Register a New User Account
Realm registers accounts differently depending on the authentication provider:
You do not need to register anonymous users.
To register an email/password user, refer to Email/Password User Registration.
If you are using Google, Facebook, Apple, or Custom JWT authentication, registration is handled by these third-party services.
Log In
You can authenticate users with App.logIn().
If successful, app.logIn returns a User object.
Anonymous User
The anonymous authentication provider
enables users to log in to your application with short-term accounts
that store no persistent personal information. To log in with anonymous
authentication, create an anonymous credential by calling
Credentials.anonymous()
and then pass the generated credential to
app.logIn.
final anonCredentials = Credentials.anonymous(); await app.logIn(anonCredentials);
If you want more than one anonymous user, set reuseCredentials: false
when creating additional anonymous credentials.
final anonUser = await app.logIn(Credentials.anonymous()); final otherAnonUser = await app.logIn(Credentials.anonymous(reuseCredentials: false));
Email/Password User
The Email/Password authentication provider
enables users to log in to your application with an email username and
a password. To log in with email/password authentication, create an
email/password credential by calling Credentials.emailPassword()
with the user's email and password.
Then pass the credential to app.logIn.
final emailPwCredentials = Credentials.emailPassword("lisa@example.com", "myStr0ngPassw0rd"); await app.logIn(emailPwCredentials);
To learn more about the complete flow of using App Services Email/Password authentication, refer to Email/Password Users.
Custom JWT User
If you have configured the Custom JWT authentication provider, you can log in using JWT credentials from an external authentication provider.
To log in with Custom JWT authentication, create a JWT credential by calling
Credentials.jwt()
on a JWT string. Then pass the credential to app.logIn.
final token = await authenticateWithExternalSystem(); final jwtCredentials = Credentials.jwt(token); final currentUser = await app.logIn(jwtCredentials);
API Key User
If you have enabled API Key authentication, you can log in using either a client or server API key.
To log in with API key authentication, create an ApiKey
credential by calling Credentials.apiKey()
on an API key string. Then pass the credential to app.logIn().
final apiKeyCredentials = Credentials.apiKey(myApiKey); final apiKeyUser = await app.logIn(apiKeyCredentials);
To generate a server API key to use in your credentials, refer to the Create a Server API Key documentation.
To work with user API keys with the same permissions as the currently logged in user, use the User.apiKeys client. You can create, fetch, delete, disable, and enable user API keys.
// Create user API key final apiKey = await user.apiKeys.create("api-key-name"); // Get existing user API key by ID // Returns `null` if no existing API key for the ID final refetchedApiKey = await user.apiKeys.fetch(apiKey.id); // Get all API keys for a user final apiKeys = await user.apiKeys.fetchAll(); // Disable API key await user.apiKeys.disable(apiKey.id); // Check if API key is enabled print(apiKey.isEnabled); // prints `false` // Enable API key await user.apiKeys.enable(apiKey.id); // Delete a user API key await user.apiKeys.delete(apiKey.id);
Custom Function User
If you have configured the Custom Function authentication provider, you can log in using custom authentication logic handled by an Atlas Function.
To log in with Custom Function authentication, pass a stringified JSON with
your custom arguments to Credentials.function().
Then pass the credential to app.logIn.
final credentials = { "username": "someUsername", }; // payload must be a JSON-encoded string final payload = jsonEncode(credentials); final customCredentials = Credentials.function(payload); final currentUser = await app.logIn(customCredentials);
Facebook User
If you have configured the Facebook authentication provider, you can log in using an existing Facebook account.
To log in with Facebook authentication, pass a Facebook access token to
Credentials.facebook().
Then pass the credential to app.logIn.
final facebookCredentials = Credentials.facebook(accessToken); final currentUser = await app.logIn(facebookCredentials);
Important
Do Not Store Facebook Profile Picture URLs
Facebook profile picture URLs include the user's access token to grant permission to the image. To ensure security, do not store a URL that includes a user's access token. Instead, access the URL directly from the user's metadata fields when you need to fetch the image.
Google User
If you have configured the Google authentication provider, you can log in using an existing Google account.
To log in with a Google authentication code, pass a Google authentication code to
Credentials.googleAuthCode().
Then pass the credential to app.logIn.
final googleAuthCodeCredentials = Credentials.googleAuthCode(authCode); final currentUser = await app.logIn(googleAuthCodeCredentials);
To log in with a Google ID token, pass a Google ID token to
Credentials.googleIdToken().
Then pass the credential to app.logIn.
final googleIdTokenCredentials = Credentials.googleIdToken(idToken); final currentUser = await app.logIn(googleIdTokenCredentials);
Apple User
If you have configured the Sign-in with Apple authentication provider, you can log in using an existing Apple account.
To log in with Apple authentication, pass an Apple access token to
Credentials.apple().
Then pass the credential to app.logIn.
final appleCredentials = Credentials.apple(idToken); final currentUser = await app.logIn(appleCredentials);
Tip
If you get a Login failed error saying that the token contains
an invalid number of segments, verify that you're passing a UTF-8-encoded
string version of the JWT.
Refresh Token Expiration
Refresh tokens expire after a set period of time. When the refresh token expires, the access token can no longer be refreshed and the user must log in again.
If the refresh token expires after the realm is open, the device will not be able to sync until the user logs in again. Your sync error handler should implement logic that catches a token expired error when attempting to sync, then redirect users to a login flow.
For information on configuring refresh token expiration, refer to Manage User Sessions in the App Services documentation.
Log a User Out
You can log out any user, regardless of the authentication provider used to log in, using User.logOut(). This method:
Deletes locally stored user credentials from the device
Immediately halts any synchronization to and from the user's realms
Because logging out halts synchronization, you should only log out after all local Realm updates have uploaded to the server.
await user.logOut();
Retrieve Current User
Once you have an authenticated user, you can retrieve the User object with the
App.currentUser
property. The currentUser object is persisted in local storage, so even if
the app shuts down after the initial authentication, you do not need to call
logIn again (unless the user logged out).
final user = app.currentUser;