Things you should know in Flutter Providers

Introduction

One crucial aspect of developing Flutter applications is managing the application’s state effectively. State refers to the data that determines how the UI should be rendered and behaves in response to user interactions. It includes variables, flags, or objects that hold information about the app’s current state, such as user input, network responses, or user preferences.

At its core, a provider is a container for data that can be accessed and updated by other widgets. It serves as the source of truth for the application’s state. Providers allow widgets to both read and listen to changes in the data they hold, ensuring that the UI remains synchronized with the underlying state.

Concepts and roles of providers

1. Manage and share application state across different parts of the widget tree.
2. Allow other widgets to access and update data.
3. Providers allow widgets to both read and listen to changes in the data they hold.
4. Providers follow the principle of “InheritedWidget,” which is a mechanism in Flutter for efficiently propagating data down the widget tree.
5. Providers also offer a level of encapsulation and isolation.
6. Providers promote separation of concerns by decoupling the UI from the state management logic.

Understanding Providers

Providers follow the principle of “InheritedWidget,” which is a mechanism in Flutter for efficiently propagating data down the widget tree. Let's take a look at the “InheritedWidget” features to clear things up.

• InheritedWidget establishes a hierarchy in the widget tree, acting as a provider of data for descendant widgets.
• When an InheritedWidget’s data changes, Flutter automatically notifies dependent widgets below it in the widget tree.
• Descendant widgets can access the data provided by an InheritedWidget by calling inheritFromWidgetOfExactType.
• InheritedWidgets trigger the automatic rebuilding of dependent widgets when the provided data changes, keeping the UI synchronized.

Providers in Flutter, specifically the provider package, simplify the implementation of InheritedWidget in several ways:

1. Providers abstract away the complexities of InheritedWidget, simplifying implementation and reducing boilerplate code.
2. Data sharing is made easy with providers, eliminating the need for explicit data passing and promoting modular code.
3. Providers automatically track dependencies and propagate data changes, optimizing performance by rebuilding only necessary widgets.
4. The provider package offers different types of providers for various scenarios, allowing developers to choose the appropriate provider type.
5. Providers seamlessly integrate with Flutter widgets and APIs, fitting smoothly into the development workflow and enabling combination with other Flutter features and libraries.

Key Features of the Provider Package

The provider package in Flutter provides several key features that make it a popular choice for state management. Here are the key features of the provider package:

1. Simplified State Management: The provider package simplifies state management in Flutter by abstracting away the complexities of managing application state. It provides a set of ready-to-use classes and utilities that streamline the process of sharing and updating data across different parts of the widget tree.
2. Various Provider Types: The package offers a variety of provider types to handle different use cases.
3. Scoped Dependency Management: The provider package allows you to define providers at different levels of the widget tree, enabling scoped data sharing. This means that you can expose data only to the relevant parts of your application, reducing coupling between widgets and improving code modularity.
4. Provider Consumer Widget: The package provides the Consumer widget, which simplifies the process of consuming data from providers. The Consumer widget automatically rebuilds its child widget whenever the data from the provider changes. This eliminates the need for manually handling setState or listening to change notifications.
5. Dependency Injection: The provider package supports dependency injection, allowing you to inject dependencies into your application using providers. This makes it easier to manage and share dependencies across your application, promoting modular and testable code.
6. DevTools Integration: The provider package integrates seamlessly with Flutter DevTools, providing enhanced debugging capabilities. It allows you to inspect and monitor the state changes in providers, making it easier to track down issues and understand the flow of data within your application.

Implementing Providers in Flutter

1. Open your Flutter project in your preferred integrated development environment (IDE). Im using Android Studio
2. Open the pubspec.yaml file located at the root of your Flutter project.
3. Inside the dependencies section of the pubspec.yaml file, add the following line:

dependencies:
  provider:         

4. Run the “flutter pub get” command to fetch and download the provider package.

You’re now ready to use the provider package in your Flutter project. You can start defining providers, and accessing data using Consumer widgets, and managing application state using the provider package's features.

5. Create a data model or object that you want to expose through a provider. For example, let’s create a simple Counter class:

class Counter {
  int value;

  Counter(this.value);

  void increment() {
    value++;
  }
}        

6. Create a provider class that extends a suitable provider type from the package. In this example, we’ll use ChangeNotifierProvider for managing the Counter object:

class CounterProvider extends ChangeNotifier {
  Counter _counter = Counter(0);

  Counter get counter => _counter;

  void incrementCounter() {
    _counter.increment();
    notifyListeners();
  }
}        

In your Flutter app’s main entry point, wrap the root widget with the provider:

void main() {
  runApp(
    ChangeNotifierProvider(
      create: (_) => CounterProvider(),
      child: MyApp(),
    ),
  );
}        

In your widget, access the data provided by the provider using a Consumer widget:

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(
          title: Text('Provider Demo'),
        ),
        body: Center(
          child: Consumer<CounterProvider>(
            builder: (context, counterProvider, _) {
              return Column(
                mainAxisAlignment: MainAxisAlignment.center,
                children: <Widget>[
                  Text(
                    'Counter Value: ${counterProvider.counter.value}',
                    style: TextStyle(fontSize: 24),
                  ),
                  SizedBox(height: 16),
                  RaisedButton(
                    child: Text('Increment'),
                    onPressed: () {
                      counterProvider.incrementCounter();
                    },
                  ),
                ],
              );
            },
          ),
        ),
      ),
    );
  }
}        

Run your Flutter app, and you’ll see the counter value displayed on the screen. Tapping the “Increment” button will update the counter value, and the UI will automatically reflect the change.

In this example, we used a ChangeNotifierProvider to manage a Counter object. The Consumer widget listens to changes in the CounterProvider, and whenever the incrementCounter method is called, the counter value is updated, and the UI is rebuilt accordingly.

You can use similar steps to create and use other provider types, such as StreamProvider for managing data streams or FutureProvider for handling future-based data. Just make sure to adjust the provider type, the provided data, and the way you access it in the widget tree based on your specific requirements.

Remember to import the necessary dependencies and follow proper widget tree structure to access the provider and its provided data correctly.

Benefits of Using Providers

1. Simplicity: Providers simplify the process of state management by abstracting away the complexities of data sharing and synchronization. They provide a straightforward and intuitive approach to managing application state, reducing the boilerplate code and making it easier to reason about the state flow in your app.
2. Centralized and Scoped State: Providers act as a centralized source of truth for the application’s state. By encapsulating data within providers, you establish a single place to manage and update the state. This centralization helps in avoiding inconsistencies and ensures that all dependent widgets have access to the latest and most accurate data. Additionally, providers support scoped data sharing, allowing you to expose data only to relevant parts of your app, reducing coupling and promoting modularity.
3. Reactive Updates: Providers enable a reactive programming model where widgets automatically update in response to changes in the underlying data. When a provider’s data changes, only the dependent widgets are rebuilt, optimizing performance. This reactive behavior ensures that the UI stays synchronized with the application state, providing a smooth and responsive user experience.
4. Simplified Widget Communication: Providers simplify the communication between widgets. Instead of passing data explicitly through constructors or callbacks, you can access the data provided by providers at any level of the widget tree. This eliminates the need for deep widget hierarchies or complex data passing logic, making your code more modular, maintainable, and easier to understand.
5. Flexibility with Provider Types: The provider package offers various types of providers, each designed to handle different use cases. Whether you need to manage simple stateful objects, handle asynchronous data streams, or work with future-based data, there’s a provider type available. This flexibility allows you to choose the appropriate provider type based on the specific requirements of your application, ensuring that you have the right tools for managing different types of data.
6. Integration with Flutter Ecosystem: Providers seamlessly integrate with other Flutter features and libraries. They work well with Flutter’s widget lifecycle, allowing you to take advantage of built-in mechanisms like build methods, setState, or didChangeDependencies. This integration ensures that providers fit smoothly into the Flutter development workflow and can be easily combined with other Flutter features and libraries, enhancing code reusability and maintainability.
7. Testing and Debugging: Providers simplify testing and debugging processes. Since providers encapsulate state and logic, it becomes easier to write unit tests for individual providers without needing to interact with the entire widget tree. Additionally, the provider package includes helpful debugging tools and features that aid in tracking and inspecting state changes during development, making it easier to identify and resolve issues.