Manage Users in Firebase

Create a user

You 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.

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

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 != nullptr) {
      // 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, current_user returns nullptr.

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 != nullptr) {
  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 != nullptr) {
  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 != nullptr) {
  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 != nullptr) {
  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 != nullptr) {
  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 != nullptr) {
  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 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.

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 != nullptr) {
  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 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.

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 != nullptr) {
  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