Manage Users in Firebase

Create a user

You have the following options for creating a new user:

From your app: Create a new user in your Firebase project by calling the CreateUserWithEmailAndPassword method or by signing in a user for the first time using a federated identity provider, such as Google Sign-In or Facebook Login.
In the Firebase console: Create a new password-authenticated user in the Security > Authentication > Users tab.

Get the currently signed-in user

The recommended way to get the current user is by setting a listener on the Auth object:

class MyAuthStateListener : public firebase::auth::AuthStateListener {
 public:
  void OnAuthStateChanged(firebase::auth::Auth* auth) override {
    firebase::auth::User user = auth->current_user();
    if (user.is_valid()) {
      // User is signed in
      printf("OnAuthStateChanged: signed_in %s\n", user.uid().c_str());
    } else {
      // User is signed out
      printf("OnAuthStateChanged: signed_out\n");
    }
    // ...
  }
};
// ... initialization code
// Test notification on registration.
MyAuthStateListener state_change_listener;
auth->AddAuthStateListener(&state_change_listener);

By using a listener, you ensure that the Auth object isn't in an intermediate state—such as initialization—when you get the current user.

You can also get the currently signed-in user by calling current_user. If a user isn't signed in, the user's is_valid method will return false.

Persist a user's credential

The user's credentials will be stored in the local keystore after a user is signed in. The local cache of user credentials can be deleted by signing the user out. The keystore is platform specific:

Apple platforms: Keychain Services.
Android: Android Keystore.
Windows: Credential Management API.
OS X: Keychain Services.
Linux: libsecret, which the user must have installed.

Get a user's profile

To get a user's profile information, use the accessor methods of an instance of firebase::auth::User. For example:

firebase::auth::User user = auth->current_user();
if (user.is_valid()) {
  std::string name = user.display_name();
  std::string email = user.email();
  std::string photo_url = user.photo_url();
  // The user's ID, unique to the Firebase project.
  // Do NOT use this value to authenticate with your backend server,
  // if you have one. Use firebase::auth::User::Token() instead.
  std::string uid = user.uid();
}

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 method. For example:

firebase::auth::User user = auth->current_user();
if (user.is_valid()) {
  for (auto it = user.provider_data().begin();
       it != user.provider_data().end(); ++it) {
    firebase::auth::UserInfoInterface profile = *it;
    // Id of the provider (ex: google.com)
    std::string providerId = profile.provider_id();

    // UID specific to the provider
    std::string uid = profile.uid();

    // Name, email address, and profile photo Url
    std::string name = profile.display_name();
    std::string email = profile.email();
    std::string photoUrl = profile.photo_url();
  }
}

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 UpdateUserProfile method. For example:

firebase::auth::User user = auth->current_user();
if (user.is_valid()) {
  firebase::auth::User::UserProfile profile;
  profile.display_name = "Jane Q. User";
  profile.photo_url = "https://example.com/jane-q-user/profile.jpg";
  user.UpdateUserProfile(profile).OnCompletion(
      [](const firebase::Future<void>& completed_future, void* user_data) {
        // We are probably in a different thread right now.
        if (completed_future.error() == 0) {
          printf("User profile updated.");
        }
      },
      nullptr);  // pass user_data here.
}

Set a user's email address

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

firebase::auth::User user = auth->current_user();
if (user.is_valid()) {
  user.UpdateEmail("user@example.com")
      .OnCompletion(
          [](const firebase::Future<void>& completed_future,
             void* user_data) {
            // We are probably in a different thread right now.
            if (completed_future.error() == 0) {
              printf("User email address updated.");
            }
          },
          nullptr);
}

Send a user a verification email

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

firebase::auth::User user = auth->current_user();
if (user.is_valid()) {
  user.SendEmailVerification().OnCompletion(
      [](const firebase::Future<void>& completed_future, void* user_data) {
        // We are probably in a different thread right now.
        if (completed_future.error() == 0) {
          printf("Email sent.");
        }
      },
      nullptr);
}

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.

Set a user's password

You can set a user's password with the UpdatePassword method. For example:

firebase::auth::User user = auth->current_user();
std::string newPassword = "SOME-SECURE-PASSWORD";

if (user.is_valid()) {
  user.UpdatePassword(newPassword.c_str())
      .OnCompletion(
          [](const firebase::Future<void>& completed_future,
             void* user_data) {
            // We are probably in a different thread right now.
            if (completed_future.error() == 0) {
              printf("password updated.");
            }
          },
          nullptr);
}

Send a password reset email

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

std::string emailAddress = "user@example.com";

auth->SendPasswordResetEmail(emailAddress.c_str())
    .OnCompletion(
        [](const firebase::Future<void>& completed_future,
           void* user_data) {
          // We are probably in a different thread right now.
          if (completed_future.error() == 0) {
            // Email sent.
          } else {
            // An error happened.
            printf("Error %d: %s", completed_future.error(),
                   completed_future.error_message());
          }
        },
        nullptr);

You can customize which email template is used in the Security > Authentication > Templates tab of the Firebase console. See Email Templates in Firebase Help Center.

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:

firebase::auth::User user = auth->current_user();
if (user.is_valid()) {
  user.Delete().OnCompletion(
      [](const firebase::Future<void>& completed_future, void* user_data) {
        if (completed_future.error() == 0) {
          // User deleted.
        } else {
          // An error happened.
          printf("Error %d: %s", completed_future.error(),
                 completed_future.error_message());
        }
      },
      nullptr);
}

You can also delete users in the Firebase console in the Security > Authentication > Users tab.

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.

When this happens, re-authenticate the user by getting new sign-in credentials from the user and passing the credentials to Reauthenticate. For example:

firebase::auth::User user = auth->current_user();

// Get auth credentials from the user for re-authentication. The example
// below shows email and password credentials but there are multiple
// possible providers, such as GoogleAuthProvider or FacebookAuthProvider.
firebase::auth::Credential credential =
    firebase::auth::EmailAuthProvider::GetCredential("user@example.com",
                                                     "password1234");

if (user.is_valid()) {
  user.Reauthenticate(credential)
      .OnCompletion(
          [](const firebase::Future<void>& completed_future,
             void* user_data) {
            if (completed_future.error() == 0) {
              printf("User re-authenticated.");
            }
          },
          nullptr);
}

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