Manage Users in Firebase

Create a user

You create a new user in your Firebase project in four ways:

Call the createUserWithEmailAndPassword() method.
Sign in a user for the first time using a federated identity provider , such as Google Sign-In, Facebook Login, or Apple.

You can also create new password-authenticated users from the Authentication section of the Firebase console , on the Users page.

Get a user's profile

To get a user's profile information, use the properties of User . There are three ways to get a User object representing the current user:

The authStateChanges , idTokenChanges and userChanges streams: your listeners will receive the current User , or null if no user is authenticated:

  FirebaseAuth 
 . 
 instance 
  
 . 
 authStateChanges 
 () 
  
 . 
 listen 
 (( 
 User 
 ? 
  
 user 
 ) 
  
 { 
  
 if 
  
 ( 
 user 
  
 != 
  
 null 
 ) 
  
 { 
  
 print 
 ( 
 user 
 . 
 uid 
 ); 
  
 } 
  
 });

When the app starts, an event fires after the user credentials (if any) from local storage have been restored, meaning that your listeners always get called when the user state is initialized. Then, whenever the authentication state changes, a new event will be raised with the updated user state.

By listening to the authentication state, you can build a user interface that reacts to these changes in authentication state. Do not place authStateChanges().listen(...) directly inside a widget's build method, as it will create a new subscription on every rebuild. If you need to update the UI in response to auth state, use a StreamBuilder :

  StreamBuilder<User 
 ? 
> ( 
 stream: 
  
 FirebaseAuth 
 . 
 instance 
 . 
 authStateChanges 
 (), 
 builder: 
  
 ( 
 BuildContext 
  
 context 
 , 
  
 AsyncSnapshot<User 
 ? 
>  
 snapshot 
 ) 
  
 { 
  
 if 
  
 ( 
 snapshot 
 . 
 hasError 
 ) 
  
 { 
  
 return 
  
 const 
  
 Text 
 ( 
 'Something went wrong' 
 ); 
  
 } 
  
 if 
  
 ( 
 snapshot 
 . 
 connectionState 
  
 == 
  
 ConnectionState 
 . 
 waiting 
 ) 
  
 { 
  
 return 
  
 const 
  
 Text 
 ( 
 "Loading..." 
 ); 
  
 } 
  
 if 
  
 ( 
 ! 
 snapshot 
 . 
 hasData 
 ) 
  
 { 
  
 return 
  
 const 
  
 SignInScreen 
 (); 
  
 } 
  
 final 
  
 user 
  
 = 
  
 snapshot 
 . 
 data 
 ! 
 ; 
  
 return 
  
 HomeScreen 
 ( 
 userId: 
  
 user 
 . 
 uid 
 ); 
 }, 
 )

This approach ensures the widget tree rebuilds automatically when the user's authentication state changes.

The UserCredential object returned by the authentication ( signIn -) methods: the UserCredential object has a user property with the current User :

  final 
  
 userCredential 
  
 = 
  
 await 
  
 FirebaseAuth 
 . 
 instance 
 . 
 signInWithCredential 
 ( 
 credential 
 ); 
 final 
  
 user 
  
 = 
  
 userCredential 
 . 
 user 
 ; 
 print 
 ( 
 user 
 ? 
 . 
 uid 
 );

The currentUser property of the FirebaseAuth instance: if you are sure the user is currently signed-in, you can access the User from the currentUser property:
```
  if 
  
 ( 
 FirebaseAuth 
 . 
 instance 
 . 
 currentUser 
  
 != 
  
 null 
 ) 
  
 { 
  
 print 
 ( 
 FirebaseAuth 
 . 
 instance 
 . 
 currentUser 
 ? 
 . 
 uid 
 ); 
 } 
 
```
The currentUser can be null for two reasons:
- The user isn't signed in.
- The auth object has not finished initializing. If you use a listener to keep track of the user's sign-in status, you don't need to handle this case.

Get a user's provider-specific profile information

To get the profile information retrieved from the sign-in providers linked to a user, use the providerData property. For example:

  if 
  
 ( 
 user 
  
 != 
  
 null 
 ) 
  
 { 
  
 for 
  
 ( 
 final 
  
 providerProfile 
  
 in 
  
 user 
 . 
 providerData 
 ) 
  
 { 
  
 // ID of the provider (google.com, apple.com, etc.) 
  
 final 
  
 provider 
  
 = 
  
 providerProfile 
 . 
 providerId 
 ; 
  
 // UID specific to the provider 
  
 final 
  
 uid 
  
 = 
  
 providerProfile 
 . 
 uid 
 ; 
  
 // Name, email address, and profile photo URL 
  
 final 
  
 name 
  
 = 
  
 providerProfile 
 . 
 displayName 
 ; 
  
 final 
  
 emailAddress 
  
 = 
  
 providerProfile 
 . 
 email 
 ; 
  
 final 
  
 profilePhoto 
  
 = 
  
 providerProfile 
 . 
 photoURL 
 ; 
  
 } 
 }

Update a user's profile

You can update a user's basic profile information—the user's display name and profile photo URL—with the update - methods. For example:

  await 
  
 user 
 ? 
 . 
 updateDisplayName 
 ( 
 "Jane Q. User" 
 ); 
 await 
  
 user 
 ? 
 . 
 updatePhotoURL 
 ( 
 "https://example.com/jane-q-user/profile.jpg" 
 );

Set a user's email address

You can set a user's email address with the updateEmail() method. For example:

  await 
  
 user 
 ? 
 . 
 updateEmail 
 ( 
 "janeq@example.com" 
 );

Send a user a verification email

You can send an address verification email to a user with the sendEmailVerification() method. For example:

  await 
  
 user 
 ? 
 . 
 sendEmailVerification 
 ();

You can customize the email template that is used in Authentication section of the Firebase console , on the Email Templates page. See Email Templates in Firebase Help Center.

It is also possible to pass state via a continue URL to redirect back to the app when sending a verification email.

Additionally you can localize the verification email by updating the language code on the Auth instance before sending the email. For example:

  await 
  
 FirebaseAuth 
 . 
 instance 
 . 
 setLanguageCode 
 ( 
 "fr" 
 ); 
 await 
  
 user 
 ? 
 . 
 sendEmailVerification 
 ();

Set a user's password

You can set a user's password with the updatePassword() method. For example:

  await 
  
 user 
 ? 
 . 
 updatePassword 
 ( 
 newPassword 
 );

Send a password reset email

You can send a password reset email to a user with the sendPasswordResetEmail() method. For example:

  await 
  
 FirebaseAuth 
 . 
 instance 
  
 . 
 sendPasswordResetEmail 
 ( 
 email: 
  
 "user@example.com" 
 );

You can customize the email template that is used in Authentication section of the Firebase console , on the Email Templates page. See Email Templates in Firebase Help Center.

It is also possible to pass state via a continue URL to redirect back to the app when sending a password reset email.

Additionally you can localize the password reset email by updating the language code on the Auth instance before sending the email. For example:

  await 
  
 FirebaseAuth 
 . 
 instance 
 . 
 setLanguageCode 
 ( 
 "fr" 
 );

You can also send password reset emails from the Firebase console.

Delete a user

You can delete a user account with the delete() method. For example:

  await 
  
 user 
 ? 
 . 
 delete 
 ();

You can also delete users from the Authentication section of the Firebase console , on the Users page.

Re-authenticate a user

Some security-sensitive actions—such as deleting an account , setting a primary email address , and changing a password —require that the user has recently signed in. If you perform one of these actions, and the user signed in too long ago, the action fails and throws a FirebaseAuthException with the code requires-recent-login . When this happens, re-authenticate the user by getting new sign-in credentials from the user and passing the credentials to reauthenticate . For example:

  // Prompt the user to re-provide their sign-in credentials. 
 // Then, use the credentials to reauthenticate: 
 await 
  
 user 
 ? 
 . 
 reauthenticateWithCredential 
 ( 
 credential 
 );

Import user accounts

You can import user accounts from a file into your Firebase project by using the Firebase CLI's auth:import command. For example:

 firebase  
auth:import  
users.json  
--hash-algo = 
scrypt  
--rounds = 
 8 
  
--mem-cost = 
 14