State Management in Flutter: Redux vs. Provider
31 May, 2023
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Introduction
In Flutter, state management involves handling and updating the application's data as well as maintaining consistency across various parts and screens. It provides developers with the ability to decide how data is shared, accessed, and modified within the application, ensuring that the user interface appropriately reflects the underlying data.
In this tutorial, we'll look at two popular Flutter state management solutions: Redux and Provider. Understanding the unique characteristics of each technique will enable you to make an informed decision when choosing the best state management approach for your Flutter project. So, let's dig in and learn about state management in Flutter!
Redux
Redux is a predictable state management model in Flutter that offers a systematic and efficient approach to managing your application's state. It provides a clear separation of concerns, making state changes more predictable and debuggable. Using Redux, developers can get a single source of truth for the state of their application, resulting in increased scalability, testability, and maintainability.
Official Github link.
At the core of Redux are three key components: actions, reducers, and store.
Actions
Actions are plain objects that represent certain events or user interactions within the application. They express the intention to change the state. An action could, for example, be "ADD_TODO" which indicates adding a new item to a to-do list, or "INCREMENT_COUNTER" to indicate incrementing a counter value. Actions have a type property that uniquely identifies the action and, if necessary, additional payload data.
Reducers
Reducers are pure functions that handle actions and update the state accordingly. A reducer calculates and returns the new state given the current state and an action. It is important to note that reducers should not modify the existing state but rather build a new state object. This immutability guarantees that the preceding state remains unchanged, allowing for quick change detection.
Store
Redux's central hub is the store. It is a container for the reducer functions and holds the application state. The store is in charge of assigning actions to appropriate reducers and initiating state modifications. It also includes ways for retrieving the current state and subscribing to state changes. Components that use the store can efficiently get and update the application state without being directly dependent on one another.
Redux creates a one-way data flow by following this approach. Actions are sent to the store, which then calls the appropriate reducers to update the state. The changed state is then returned to the components, causing UI modifications as needed. This predictable pattern makes it easier to reason about how state changes occur, debug problems, and ensure consistency across the program.
An example implementation of Redux in a Flutter app
To show how Redux can be implemented in a Flutter app, let's consider a simple counter application.
To import and use Redux in a Flutter app, follow these steps:
Add the Redux dependency to your pubspec.yaml file:
dependencies:
flutter_redux: ^0.8.2
redux: ^5.0.0Run flutter pub get in your terminal to fetch the dependencies.
Import the necessary packages in your Dart file:
import 'package:flutter/material.dart';
import 'package:flutter_redux/flutter_redux.dart';
import 'package:redux/redux.dart';Define the State:
Start by specifying the counter's state, which includes the current count value. A simple class can express the state in this case:
class CounterState {
final int count;
CounterState(this.count);
}Define Actions:
Define the actions that can change the state next. We'll have two actions in this example: IncrementAction and DecrementAction. These actions express an intent to increment or reduce the counter:
class IncrementAction {}
class DecrementAction {}Define Reducers:
Create reducers to handle the actions and update the state. In this scenario, we'll have a single reducer function that takes in the current state and an action and produces a new state:
CounterState counterReducer(CounterState state, dynamic action) {
if (action is IncrementAction) {
return CounterState(state.count + 1);
} else if (action is DecrementAction) {
return CounterState(state.count - 1);
}
return state;
}Creating the Store:
Create a store that manages the dispatching of actions to the reducer and holds the state. The store is in charge of maintaining the state and informing subscribers of any changes:
final store = Store<CounterState>(
counterReducer,
initialState: CounterState(0),
);Dispatch Actions and Subscribe to State Changes:
To update the UI, dispatch actions to modify the state and subscribe to state changes in the Flutter app.
Here's an example of how you can do it in a Flutter widget:
The StoreProvider widget in this example adds the store to the widget tree, giving access to the store across the program. The StoreConnector widget links the widget to the store and changes the state (in this case, the count value) to the desired type. When the buttons are pressed, the UI can reflect the current state and dispatch actions to change the state
Provider
Provider is a flexible and lightweight Flutter state management solution that provides a simple and effective way to manage your app's state. It is constructed on top of the InheritedWidget, which allows data to be quickly passed down the widget tree.
Official Github link.
Core Concepts of Provider in Flutter:
- ChangeNotifier
- Consumer
- Provider widgets.
ChangeNotifier:
ChangeNotifier is a Flutter framework class that implements the Observable pattern. It enables you to construct a model class that holds your app's state and tells its listeners when the state changes. To utilize ChangeNotifier, extend the ChangeNotifier class and add the @protected annotation to the attributes that reflect the state.
Example:
class MyModel extends ChangeNotifier {
@protected
int _count = 0;
int get count => _count;
void increment() {
_count++;
notifyListeners();
}
void decrement() {
_count--;
notifyListeners();
}
}Consumer:
The Consumer widget is used to monitor changes in a ChangeNotifier's status. When the notified state changes, it rebuilds its child widget. The Consumer widget accepts a builder function as a child and returns the most recent state of the supplied ChangeNotifier to it. You can easily access and use the state within your widget hierarchy by using the Consumer widget.
Example:
Consumer<MyModel>(
builder: (context, myModel, child) {
return Text('Count: ${myModel.count}');
},
)Provider:
The Provider widget is used to provide a ChangeNotifier instance to its children. It enables you to share the state of a widget across multiple widgets without having to manually pass the instance down the widget tree. Wrapping the root widget or a specified area of your widget tree in Provider makes the provided instance of the ChangeNotifier available to all descendants that use the Consumer widget.
Example:
Provider(
create: (context) => MyModel(),
child: MyApp(),
)The create parameter is used in this example to add a new instance of the MyModel class to the widget tree. Any descendent widget that uses the Consumer widget can access the given instance.
You can easily manage the state of your Flutter app by using the ChangeNotifier, Consumer, and Provider widgets. ChangeNotifier allows you to construct a model class that contains the state, Consumer listens for changes in the state and updates the UI accordingly, and Provider allows you to share the state across several widgets. This combination enables Flutter applications to manage state in a flexible and efficient manner.
Comparison between Redux and Provider
When it comes to state management in Flutter, two popular options are Redux and Provider. Let's compare them to understand their differences and benefits:
Architecture:
Redux adheres to a rigid architectural pattern that is centered on one-way data flow. It splits the state into a single, centralized store and modifies the state using actions and reducers.
Provider, on the other hand, is a more adaptable and lightweight solution that does not impose a certain architectural pattern. It enables you to manage state using a variety of methods, including ChangeNotifier, Stream, Future, and even simple Dart objects.
Complexity:
Redux: Due to its predetermined architectural pattern, Redux may have a longer learning curve. It requires the creation of actions, reducers, and a store, which may be excessive for small to medium-sized programs.
Provider: Provider provides a more straightforward and intuitive method to state management. It reduces some of the repetitive code required by Redux and enables for easier implementation, particularly for smaller projects.
Scalability:
Redux: Redux is highly scalable and ideal for large and complicated applications. Because of the rigorous separation of concerns and one-way data flow, it is easier to make sense of and maintain as the app expands.
Provider: Provider is also scalable, but it offers more flexibility, which can result in different implementation patterns. To retain scalability as the app size grows, careful organization and management of state objects are required.
Performance:
Redux: Redux improves efficiency by allowing for immutability and selective updates. It ensures that when a certain part of the state changes, only the components that rely on that section are re-rendered.
Provider: The Provider class is designed to be efficient by utilizing Flutter's efficient widget-rebuilding techniques. It is possible to reduce needless rebuilds and increase overall efficiency by using the right ValueNotifier or ChangeNotifier.
Community and Ecosystem:
Redux: Redux has a huge and active community, rich documentation, and a wide selection of packages and plugins available. It is widely used in the Flutter ecosystem and provides a wealth of resources and tools.
Provider: Provider is gaining traction in the Flutter community and has an expanding ecosystem of packages and resources. Although it does not have the same amount of popularity as Redux, it has a strong community and is always evolving.
Conclusion
Finally, the decision between Redux and Provider is determined by the complexity and special needs of your app. Redux may be a better option if you prefer a more structured approach with a well-defined design. Provider, on the other hand, is a suitable solution if you seek simplicity, flexibility, and lightweight state management.
If you have any questions regarding Flutter or anything data related, you can reach out to me on Twitter and Showwcase.
FAQ's
- When should I choose Redux for state management in Flutter?
When you have a large-scale application with complicated state interactions, several levels of nesting, and the need for rigorous separation of concerns, Redux is a fantastic solution. Redux is a distinct architectural style, enforces one-way data flow, and has a large ecosystem of middleware and tools. It is especially useful for programs that require a lot of state management.
- When should I choose Provider for state management in Flutter?
Provider is appropriate for projects of various sizes and complexity. It provides a more lightweight and flexible approach, making it easier to develop and deploy for tiny to medium-sized apps. Provider is especially handy when you want a more straightforward and intuitive state management solution that does not require a predetermined architectural pattern like Redux.
- Can Redux and Provider be used together in a Flutter app?
Yes, Redux and Provider can coexist in a Flutter app. You can use Provider to link certain widget tree components to Redux's store and dispatch actions as needed. Provider can make it easier to share state instances and integrate Redux into your Flutter project.
- Which state management approach offers better performance, Redux, or Provider?
When built appropriately, both Redux and Provider can provide good performance. Redux improves efficiency by using immutability and selective updates to ensure that only the components that rely on a specific section of the state are re-rendered. In contrast, Provider makes use of Flutter's efficient widget-rebuilding techniques. The real performance is determined by aspects like as the app's complexity, how state updates are handled, and how effectively the UI is built and updated.