Why Flutter Bloc Not Updating State When Used with Freezed?

Are you stuck with the frustrating issue of Flutter Bloc not updating the state when used with Freezed? You’re not alone! Many developers have faced this problem, and it’s not because of a bug in either Flutter Bloc or Freezed, but rather due to a misunderstanding of how these two powerful libraries work together. In this article, we’ll dive deep into the world of state management and explore the reasons behind this issue. By the end of this article, you’ll be able to identify and resolve the problem, and your Flutter app will be back to its usual awesomeness!

What is Flutter Bloc?

Flutter Bloc is a state management library for Flutter that helps you manage your app’s state in a predictable and scalable way. It’s built on top of the BLoC (Business Logic Component) architecture, which separates your app’s business logic from its widgets. With Flutter Bloc, you can easily handle events, update your app’s state, and notify your widgets of changes.

What is Freezed?

Freezed is a code generator for immutable classes in Dart. It allows you to define your classes using a simple, concise syntax, and then generates the boilerplate code for you. Freezed is particularly useful when working with Flutter Bloc, as it enables you to create immutable models that can be easily updated and notified to your widgets.

The Problem: Why Flutter Bloc is Not Updating the State?

So, you’ve set up your Flutter Bloc architecture, defined your events, states, and models using Freezed, and written your widget code to display the data. But, when you trigger an event, the state doesn’t seem to be updating. You’ve tried debugging, checking your code multiple times, and even searched the internet for answers, but nothing seems to work.

Don’t worry; we’ve all been there! There are a few common reasons why Flutter Bloc might not be updating the state when used with Freezed. Let’s explore them one by one:

Reason 1: Incorrectly Defined Models

One of the most common mistakes is incorrectly defining your models using Freezed. When you define a model with Freezed, you need to make sure that you’re using the correct syntax and annotations. For example:

@freezed
abstract class User with _$User {
  factory User({
    @required String id,
    @required String name,
  }) = _User;

  factory User.fromJson(Map<String, dynamic> json) => _$UserFromJson(json);
}

In the above example, we’ve defined a `User` model with two properties: `id` and `name`. Notice how we’ve used the `@freezed` annotation to indicate that this class should be generated with Freezed. We’ve also defined a `fromJson` factory method to deserialize the model from JSON data.

However, if you forget to add the `@required` annotation to your properties, or misspell the property names, your model won’t be generated correctly, and Flutter Bloc won’t be able to update the state.

Reason 2: Incorrectly Implemented Bloc

Another common mistake is incorrectly implementing the Bloc class. When you define a Bloc, you need to make sure that you’re extending the correct class and implementing the correct methods. For example:

class UserBloc extends Bloc<UserEvent, UserState> {
  @override
  UserState get initialState => UserState.loaded(users: []);

  @override
  Stream<UserState> mapEventToState(UserEvent event) async* {
    if (event is LoadUsersEvent) {
      final users = await _loadUsersFromApi();
      yield UserState.loaded(users: users);
    }
  }
}

In the above example, we’ve defined a `UserBloc` class that extends the `Bloc` class from Flutter Bloc. We’ve also implemented the `initialState` property and the `mapEventToState` method, which handles the event and updates the state accordingly.

However, if you forget to implement the `mapEventToState` method or incorrectly define the event and state types, your Bloc won’t be able to update the state.

Reason 3: Incorrectly Used Equatable

When you use Freezed to generate your models, you need to make sure that you’re using the `Equatable` package to define equality between objects. For example:

import 'package:equatable/equatable.dart';

@freezed
abstract class User with _$User, Equatable {
  factory User({
    @required String id,
    @required String name,
  }) = _User;

  factory User.fromJson(Map<String, dynamic> json) => _$UserFromJson(json);

  @override
  List<Object> get props => [id, name];
}

In the above example, we’ve added the `Equatable` mixin to our `User` model and overridden the `props` property to define the properties that should be used for equality checking.

However, if you forget to add the `Equatable` mixin or incorrectly define the `props` property, your model won’t be correctly updated by Flutter Bloc.

Solutions and Best Practices

Now that we’ve explored the common reasons why Flutter Bloc might not be updating the state when used with Freezed, let’s discuss some solutions and best practices to help you avoid these issues:

Solution 1: Verify Your Models

The first step to resolving the issue is to verify that your models are correctly defined using Freezed. Make sure that you’re using the correct syntax and annotations, and that your models are being generated correctly.

Solution 2: Verify Your Bloc Implementation

Next, verify that your Bloc implementation is correct. Make sure that you’re extending the correct class, implementing the correct methods, and handling events correctly.

Solution 3: Verify Equatable Configuration

Finally, verify that you’re using the `Equatable` package correctly. Make sure that you’ve added the `Equatable` mixin to your models, and that you’ve overridden the `props` property correctly.

Best Practice 1: Use the Correct Packages

Make sure that you’re using the correct packages and versions in your project. Use the latest versions of Flutter Bloc, Freezed, and Equatable to ensure that you have the latest features and bug fixes.

Best Practice 2: Follow the Documentation

Follow the official documentation for Flutter Bloc, Freezed, and Equatable to ensure that you’re implementing the correct architecture and syntax.

Best Practice 3: Test Your Code

Test your code thoroughly to ensure that it’s working as expected. Use unit tests, widget tests, and integration tests to verify that your state is being updated correctly.

Conclusion

In conclusion, Flutter Bloc not updating the state when used with Freezed is a common issue that can be resolved by verifying your models, Bloc implementation, and Equatable configuration. By following the best practices outlined in this article, you can ensure that your Flutter app is using the correct state management architecture and that your state is being updated correctly.

Remember, state management is a crucial aspect of building scalable and maintainable Flutter apps. By using Flutter Bloc, Freezed, and Equatable together, you can create a robust and efficient state management architecture that makes your app development process easier and more enjoyable.

Library	Purpose
Flutter Bloc	State management architecture
Freezed	Immutable model generation
Equatable	Equality checking and hashing

Additional Resources

For further learning and exploration, check out the following resources:

• Flutter Bloc Documentation
• Freezed Documentation
• Equatable Documentation
• Flutter State Management Documentation

Final Thoughts

In this article, we’ve explored the common reasons why Flutter Bloc might not be updating the state when used with Freezed, and discussed the solutions and best practices to resolve the issue. By following these guidelines and using the correct packages and architecture, you can ensure that your Flutter app is using the correct state management approach and that your state is being updated correctly.

Happy coding, and remember to keep exploring and learning!

Frequently Asked Question

Getting stuck with Flutter_bloc not updating state when using Freezed? Don’t worry, we’ve got you covered! Here are some frequently asked questions and answers to help you troubleshoot the issue.