Managing State in Flutter Using BLoC Pattern/

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User Cubit

User Cubit

Learn how to use Cubits to manage user authentication and state in a Flutter app using the repository pattern and fluuter_bloc library.

We'll cover the following...

We will begin by implementing the UserCubit, which manages the user state. The application listens to this state, showing the login screen if the user is logged out and displaying the home screen if the user is logged in.

Cubits, like Blocs, have states. We generate these states in the same way as Bloc states. The only difference between Cubits and Blocs is that instead of listening to event streams, we define functions that can be called within our code.

UserState

The UserCubit will emit several states, all of which extend the UserState abstract class.

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import 'package:ecommerce/models/user.dart';
abstract class UserState {}
class UserInitial extends UserState {}
class UserSignedIn extends UserState {
  final User user;
  UserSignedIn(this.user);
}
class UserSignedOut extends UserState {}
class UserLoading extends UserState {}
class UserError extends UserState {
  final String message;
  UserError(this.message);
}

Here’s what the code above does:

  • Lines 1–3: Import the User model and define an abstract class UserState.

  • Lines 5: Define the subclass UserInitial that represents the initial state of the UserCubit.

  • Lines 7–11: Define the subclass UserSignedIn that represents the state emitted when the user successfully signs in. It includes a User object to represent the signed-in user.

  • Line 13: Define the subclass UserSignedOut that represents the state emitted when the user logs out of the app.

  • Line 15: Define the subclass UserLoading that represents the state emitted while the authentication service is working on authenticating the user.

  • Lines 17–21: Define the subclass UserError that represents the state emitted when there is an error signing in or creating new users. It includes a String message to provide more ...

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