states_rebuilder 4.4.0 states_rebuilder: ^4.4.0 copied to clipboard
a simple yet powerful state management technique for Flutter
States_rebuilder
Code Clean | Performance |
---|---|
• Separation of UI & business logic | ◦ Support for immutable / mutable state |
• Coding business logic in pure Dart | ◦ Predictable and controllable |
• Zero Boilerplate without code-generation | ◦ Strictly rebuild control |
User-friendly | Effective Production |
---|---|
◦ Elegant and lightweight syntax | • Super easy for CRUD development |
◦ SetState & Animation in StatelessWidget |
• User authentication and authorization |
◦ Navigation without BuildContext |
• App themes, multi-langs management |
◦ Built-in dependency injection system | • Easy to test, mock the dependencies |
Table of Contents
- Getting Started with States_rebuilder
- Breaking Changes
- A Quick Tour of states_rebuilder API
- Business logic and state injection
- State change and notification
- State subscription and Reactive Builders
- State persistence
- Undo and redo immutable state
- Route management
- Create, Read, Update and Delete items from backend service
- Authentication and authorization
- Dynamic theme switching
- App internationalization
- Animation in StatelessWidget:
- Working with TextFields and Form validation
- Working with scrollable view
- Working with page and tab views
- Test and injected state mocking
- Examples:
Getting Started with States_rebuilder #
- Install this package:
- With Flutter:
$ flutter pub add states_rebuilder
- Or: add into your pubspec.yaml:
dependencies:
states_rebuilder: ...
- Import it in any Dart code:
import 'package:states_rebuilder/states_rebuilder.dart';
- Basic use case:
/* ------------- 🗄️ Plain Data Class ------------- */
class Counter {
final int value;
Counter(this.value);
@override
String toString() {
return 'Counter($value)';
}
}
/* -------------- 🤔 Business Logic -------------- */
//🚀 It is immutable
@immutable
class ViewModel {
// Inject a reactive state of type int.
// Works for all primitives, List, Map and Set
final counter1 = 0.inj();
// For non primitives and for more options
final counter2 = RM.inject<Counter>(
() => Counter(0),
// State will be redone and undone
undoStackLength: 8,
// Build-in logger
debugPrintWhenNotifiedPreMessage: 'counter2',
);
//A getter that uses the state of the injected counters
int get sum => counter1.state + counter2.state.value;
incrementCounter1() {
counter1.state++;
}
incrementCounter2() {
counter2.state = Counter(counter2.state.value + 1);
}
}
/* ------------------- 👍 Setup ------------------- */
/// NOTE: As [ViewModel] is immutable and final, it is safe to globally instantiate it.
//🚀 The state of counter1 and counter2 will be auto-disposed when no longer in use.
// They are testable and mockable.
final viewModel = ViewModel();
/* -------------------- 👀 UI -------------------- */
///🚀 Just use [ReactiveStatelessWidget] widget instead of StatelessWidget.
// CounterApp will automatically register in any state consumed in its widget child
// branch, regardless of its depth, provided the widget is not lazily loaded as
// in the builder method of the ListView.builder widget.
class CounterApp extends ReactiveStatelessWidget {
const CounterApp();
@override
Widget build(BuildContext context) {
return Column(
mainAxisAlignment: MainAxisAlignment.spaceEvenly,
children: [
const Counter1View(),
const Counter2View(),
Text('🏁 Result: ${viewModel.sum}'), // Will be updated when sum changes
],
);
}
}
// Child 1 - Plain StatelessWidget
class Counter1View extends StatelessWidget {
const Counter1View({Key? key}) : super(key: key);
@override
Widget build(BuildContext context) {
return Column(
children: [
ElevatedButton(
child: const Text('🏎️ Counter1 ++'),
onPressed: () => viewModel.incrementCounter1(),
),
// Listen to the state from parent
Text('Counter1 value: ${viewModel.counter1.state}'),
],
);
}
}
// Child 2 - Plain StatelessWidget
class Counter2View extends StatelessWidget {
const Counter2View({Key? key}) : super(key: key);
@override
Widget build(BuildContext context) {
return Column(
children: [
ElevatedButton(
child: const Text('🏎️ Counter2 ++'),
onPressed: () => viewModel.incrementCounter2(),
),
ElevatedButton(
child: const Text('⏱️ Undo'),
onPressed: () => viewModel.counter2.undoState(),
),
Text('Counter2 value: ${viewModel.counter2.state.value}'),
],
);
}
}
Breaking Changes #
Breaking Version | Support | Link |
---|---|---|
4.0 | ✅ Least version | Doc |
3.0 | Legacy (2020-09-04) | Doc |
2.0 | Legacy (2020-06-02) | Doc |
- Use of modern version is recommended for getting maximum performance & development experience with flutter 2.0.
A Quick Tour of states_rebuilder API #
Business logic and state injection #
Business logic classes are independent from any external library. They are independent even from
states_rebuilder
itself.
The specificity of states_rebuilder
is that it has practically no boilerplate. It has no boilerplate to the point where you do not have to monitor the asynchronous state yourself. You do not need to add fields to hold for example onLoading
, onLoaded
, onError
states. states_rebuilder
automatically manages these asynchronous statuses and exposes the isIdle
, isWaiting
, hasError
and hasData
getters and onIdle
, onWaiting
, onError
and onData
hooks for use in the user interface logic.
With
states_rebuilder
, you write business logic without bearing in mind how the user interface would interact with it.
This is a typical simple business logic class:
class Foo { // Don't extend any other library specific class
int mutableState = 0; // The state can be mutable
final int immutableState; // Or it can be immutable (no difference)
Foo(this.immutableState);
Future<int> fetchSomeThing async(){
// No need for any kind of async state tracking variables
return repository.fetchSomeThing();
// No need for any kind of notification
}
Stream<int> streamSomeThing async*(){
// Methods can return stream, future, or simple sync objects,
// states_rebuilder treats them equally
}
}
To make the Foo
object reactive, we simply inject it using global functional injection:
final Injected<Foo> foo = RM.inject<Foo>(
()=> Foo(),
onInitialized : (Foo state) => print('Initialized'),
// Default callbacks for side effects.
onSetState: On.all(
onIdle: () => print('Is idle'),
onWaiting: () => print('Is waiting'),
onError: (error) => print('Has error'),
onData: (Foo data) => print('Has data'),
),
// It is disposed when no longer needed
onDisposed: (Foo state) => print('Disposed'),
// To persist the state
persist:() => PersistState(
key: '__FooKey__',
toJson: (Foo s) => s.toJson(),
fromJson: (String json) => Foo.fromJson(json),
// Optionally, throttle the state persistance
throttleDelay: 1000,
),
// middleSnapState as a middleWare place used to
// track and log state lifecycle and transitions.
// It can also be used to return another state created
// from the current state and the next state.
middleSnapState: (middleSnap) {
middleSnap.print(); //Build-in logger
// Example of simple email validation
if (middleSnap.nextSnap.hasData) {
if (!middleSnap.nextSnap.data.contains('@')) {
return middleSnap.nextSnap.copyToHasError(
Exception('Enter a valid Email'),
);
}
}
},
);
// For simple injection you can use `inj()` extension:
final foo = Foo().inj<Foo>();
final isBool = false.inj();
final string = 'str'.inj();
final count = 0.inj();
Injected
interface is a wrapper class that encloses the state we want to inject. The state can be mutable or immutable.
Injected state can be instantiated globally or as a member of classes. They can be instantiated inside the build method without losing the state after rebuilds.
To inject a state, you use
RM.inject
,RM.injectFuture
,RM.injectStream
orRM.injectFlavor
.
The injected state even if it is injected globally, it has a lifecycle. It is created when first used and destroyed when no longer used. Between the creation and the destruction of the state, it can be listened to and mutated to notify its registered listeners.
When the state is disposed of, its list of listeners is cleared, and if the state is waiting for a Future or subscribed to a Stream, it will cancel them to free resources.
Injected state can depend on other Injected states and recalculate its state and notify its listeners whenever any of its Inject model that it depends on emits a notification.
🗎 See more detailed information about the RM.injected API.
State change and notification #
To mutate the state and notify to listener(s):
// Set state inside any callback:
foo.state = newFoo;
// For more options
foo.setState(
(s) => s.fetchSomeThing(),
// Run `side-effect` during setState
onSetState: On.waiting(()=> showSnackBar()),
debounceDelay : 400,
);
// For boolean type state
foo.toggle();
The state when mutated emits a notification to its registered listeners. The emitted notification has a boolean flag to describe is status :
isIdle
: the state was first created and no notification has been emitted yet.isWaiting
: the state is waiting for an async task to end.hasError
: the state mutation has ended with an error.hasData
: the state mutation has ended with valid data.isActive
: the state had data at least one time.
🗎 See more detailed information about setState API.
You can notify listeners without changing the state using :
foo.notify();
You can also refresh the state to its initial state and reinvoke the creation function then notify listeners using:
foo.refresh();
refresh
is useful to re-execute async data fetching to get the updated data from a server. Typical use is the refresh a ListView display.
If the state is persisted, calling refresh
will delete the persisted state and replace it with the newly created one.
Calling refresh
will cancel any pending async task from the state before refreshing.
🗎 See more detailed information about the refresh API.
State subscription and Reactive Builders #
There are two ways to for get your widget rebuilds by state:
Widget Builders | Style | Link |
---|---|---|
OnReactive , ReactiveStatelessWidget |
👩🏻💻 By default | Finish him! |
OnBuilder |
👨🏻🚒 Strictly to target widget | Get Over Here! |
OnReactive widget and ReactiveStatelessWidget #
To listen to an injected state and rebuild a part of the widget tree, just wrap that part of the widget tree inside OnReactive
widget:
final counter1 = RM.inject<int>(()=> 0) // Equivalent to 0.inj();
final counter2 = 0.inj(); // Or: using extension style
int get sum => counter1.state + counter2.state;
// In the widget tree:
Column(
children: [
OnReactive( // Will listen to counter1
()=> Text('${counter1.state}');
),
OnReactive( // Will listen to counter2
()=> Text('${counter2.state}');
),
OnReactive( // Will listen to both counter1 and counter2
()=> Text('$sum');
)
]
)
Inside OnReactive
you can call any of the available state status flags (isWaiting
, hasError
, hasData
, ...) or just simply use onAll
and onOrElse
methods:
// Option 1: I do it by myself! 😤
OnReactive(
()=> {
if(myModel.isWaiting){
return WaitingWidget();
}
if(myModel.hasError){
return ErrorWidget();
}
return DataWidget();
}
)
// Option 2: use onAll method: (defined all status)
OnReactive(
()=> myModel.onAll(
onWaiting: ()=> WaitingWidget(),
onError: (err, refreshErr)=> ErrorWidget(),
onData: (data)=> DataWidget(),
);
)
// Option 3: use onOrElse method: (expected or undefined status)
OnReactive(
()=> myModel.onOrElse(
onData: (data)=> DataWidget(),
orElse: ()=> IndicatorWidget(),
);
)
Similar to OnReactive
widget there is the abstract widget ReactiveStatelessWidget
. When the ReactiveStatelessWidget
is used instead of StatelessWidget
, the widget becomes reactive and implicitly tracks its listeners no matter how deep in the widget tree they are provided that the widget is not loaded lazily such as inside the builder
method of the ListView.builder
widget:
class MyWidget extends ReactiveStatelessWidget {
@override
Widget build(BuildContext context) {
return Column(
children: [
Text('${counter1.state}'),
Text('${counter2.state}'),
Text('$sum'),
]
);
}
}
OnBuilder Builder #
In most cases OnReactive
do the job. Nevertheless, if you want to explicitly specify the listeners you want to listen to, use OnBuilder
widget.
OnBuilder(
listenTo: myState,
// Called whenever myState emits a notification
builder: () => Text('${counter.state}'),
sideEffects: SideEffects(
initState: () => print('initState'),
onSetState: (snapState) => print('onSetState'),
onAfterBuild: () => print('onAfterBuild'),
dispose: () => print('dispose'),
),
shouldRebuild: (oldSnap, newSnap) {
return true;
},
debugPrintWhenRebuild: 'myState',
),
If you want to listen to many injected states use listenToMany
parameter.
In this case onBuilder
will react to a combined state of all injected states.
OnBuilder.all(
listenToMany: [myState1, myState2],
onWaiting: () => Text('onWaiting'), // Will be invoked if at least one state is waiting
onError: (err, refreshError) => Text('onError'), // Will be invoked if at least on state has error
onData: (data) => Text(myState.state.toString()), // Will be invoked if all states have data.
),
All onError callbacks expose a refresher. It can be used to refresh the error; that is recalling the last function that caused the error.
If you want to optimize widget rebuild and prevent some part of the child widget tree from unnecessary rebuilding, use Child
, Child2
, Child3
widget.
Child(
(child) => OnReactive(
() => Colum(
children: [
Text('model.state'), // This part will rebuild
child, // This part will not rebuild
],
),
),
child: WidgetNotToRebuild(),
);
You can make your state widget-wise and override it to present different branches of the widget tree.
final items = [1,2,3];
final item = RM.inject(()=>null);
class App extends StatelessWidget{
build (context){
return ListView.builder(
itemCount: items.length,
itemBuilder: (BuildContext context, int index) {
return item.inherited( // Inherited uses the `InheritedWidget` concept
stateOverride: () => items[index],
builder: () {
return const ItemWidget();
// Inside ItemWidget you can use the buildContext to get
// the right state for each widget branch using:
// This Element owner of context is registered to item model.
item.of(context);
// Or: this Element owner of context is not registered to item model.
item(context);
}
);
},
);
}
}
State persistence #
To Persist the state and retrieve it when the app restarts,
final model = RM.inject<MyModel>(
()=>MyModel(),
persist:() => PersistState(
key: 'modelKey',
toJson: (MyModel s) => s.toJson(),
fromJson: (String json) => MyModel.fromJson(json),
// Optionally, throttle the state persistance
throttleDelay: 1000,
),
);
You can manually persist or delete the state
model.persistState();
model.deletePersistState();
Undo and redo immutable state #
Note: you should first set undoStackLength:
from RM.inject
model.undoState();
model.redoState();
🗎 See more detailed information about undo redo state.
Route management #
To navigate, show dialogs and snackBars without BuildContext
:
RM.navigate.to(HomePage());
RM.navigate.to('/namePage');
RM.navigate.toDialog(AlertDialog( ... ));
RM.scaffoldShow.snackbar(SnackBar( ... ));
You can easily change page transition animation, using one of the predefined TransitionBuilder or just define yours.
You can use dynamic segments with named routing
return MaterialApp(
navigatorKey: RM.navigate.navigatorKey,
onGenerateRoute: RM.navigate.onGenerateRoute({
'/': (_) => LoginPage(),
'/posts': (_) => RouteWidget(
routes: {
'/:author': (RouteData data) {
final queryParams = data.queryParams;
final pathParams = data.pathParams;
final arguments = data.arguments;
// Or:
// Inside a child widget of AuthorWidget :
//
// context.routeQueryParams;
// context.routePathParams;
// context.routeArguments;
return AuthorWidget();
},
'/postDetails': (_) => PostDetailsWidget(),
},
),
'/settings': (_) => SettingsPage(),
}),
);
In the UI:
RM.navigate.to('/'); // => renders LoginPage()
RM.navigate.to('/posts'); // => 404 error
RM.navigate.to('/posts/foo'); // => renders AuthorWidget(), with pathParams = {'author' : 'foo' }
RM.navigate.to('/posts/postDetails'); // => renders PostDetailsWidget(),
// If you are in AuthorWidget you can use relative path (name without the back slash at the beginning)
RM.navigate.to('postDetails'); // => renders PostDetailsWidget(),
RM.navigate.to('postDetails', queryParams : {'postId': '1'}); // => renders PostDetailsWidget(),
Create, Read, Update and Delete items from backend service #
-
To Create, Read, Update and Delete (CRUD) from backend or DataBase,
final products = RM.injectCRUD<Product, Param>( ()=> MyProductRepository(), // Implements ICRUD<Product, Param> readOnInitialization: true, // Optional (Default is false) );
// READ products.crud.read(param: (param)=> NewParam()); // CREATE products.crud.create(NewProduct()); // UPDATE products.crud.update( where: (product) => product.id == 1, set: (product)=> product.copyWith(...), ); // DELETE products.crud.delete( where: (product) => product.id == 1, isOptimistic: false, // Optional (Default is true) );
Authentication and authorization #
To authenticate and authorize users,
final user = RM.injectAuth<User, Param>(
()=> MyAuthRepository(),// Implements IAuth<User, Param>
unSignedUser: UnsignedUser(), // If null-safety it's `null`
onSigned: (user)=> // Navigate to home page,
onUnsigned: ()=> // Navigate to Auth Page,
autoSignOut: (user)=> Duration(seconds: user.tokenExpiryDate)
);
// Sign up
user.auth.signUp((param)=> Param());
// Sign in
user.auth.signIn((param)=> Param());
// Sign out
user.auth.signOut();
Dynamic theme switching #
To dynamically switch themes,
final theme = RM.injectTheme<String>(
lightThemes : {
'simple': ThemeData.light( ... ),
'solarized': ThemeData.light( ...),
},
darkThemes: {
'simple': ThemeData.dark( ... ),
'solarized': ThemeData.dark( ...),
};
themeMode: ThemeMode.system;
persistKey: '__theme__',
);
// Choose the theme
theme.state = 'solarized'
// Toggle between dark and light mode of the chosen them
theme.toggle();
App internationalization #
To internationalize and localize your app:
// U.S. English
class EnUS {
final helloWorld = 'Hello world';
}
// Spanish
class EsEs implements EnUs{
final helloWorld = 'Hola Mondo';
}
final i18n = RM.injectI18N<EnUS>(
{
Local('en', 'US'): ()=> EnUS(); // Can be async
Local('es', 'ES'): ()=> EsES();
};
persistKey: '__lang__', // Local persistance of language
);
In the UI:
Text(i18n.of(context).helloWorld);
// Choose the language
i18n.locale = Local('es', 'Es');
// Or: choose the system language
i18n.locale = SystemLocale();
Animation in StatelessWidget: #
Implicit and explicit animation #
final animation = RM.injectAnimation(
duration: const Duration(seconds: 1),
curve: Curves.linear,
);
In the UI: For Implicit animation
Center(
child: OnAnimationBuilder(
listenTo: animation,
builder: (animate) => Container(
// Animate is a callable class
width: animate.call(selected ? 200.0 : 100.0),
height: animate(selected ? 100.0 : 200.0, 'height'),
color: animate(selected ? Colors.red : Colors.blue),
alignment: animate(selected ? Alignment.center : AlignmentDirectional.topCenter),
child: const FlutterLogo(size: 75),
),
),
),
For explicit animation
OnAnimationBuilder(
listenTo: animation,
builder: (animate) => Transform.rotate(
angle: animate.formTween(
(currentValue) => Tween(begin: 0, end: 2 * 3.14),
)!,
child: const FlutterLogo(size: 75),
),
),
Working with TextFields and Form validation #
To deal with TextFields and Form validation
final email = RM.injectTextEditing():
final password = RM.injectTextEditing(
validator: (String? value) {
if (value!.length < 6) {
return "Password must have at least 6 characters";
}
return null;
},
);
final form = RM.injectForm(
autovalidateMode: AutovalidateMode.disable,
autoFocusOnFirstError: true,
submit: () async {
// This is the default submission logic:
// 1. it may be override when calling form.submit( () async { });
// 2. it may contains server validation.
await serverError = authRepository.signInWithEmailAndPassword(
email: email.text,
password: password.text,
);
// After server validation
if(serverError == 'Invalid-Email'){
email.error = 'Invalid email';
}
if(serverError == 'Weak-Password'){
email.error = 'Password must have more the 6 characters';
}
},
onSubmitting: () {
// Called while waiting for form submission,
},
onSubmitted: () {
// Called after form is successfully submitted
// for example: navigation to user page
}
);
In the UI:
OnFormBuilder(
listenTo: form,
builder: () => Column(
children: <Widget>[
TextField(
focusNode: email.focusNode,
controller: email.controller,
decoration: InputDecoration(
errorText: email.error,
),
onSubmitted: (_) {
// Request the password node
password.focusNode.requestFocus();
},
),
TextField(
focusNode: password.focusNode,
controller: password.controller,
decoration: new InputDecoration(
errorText: password.error,
),
onSubmitted: (_) {
// Request the submit button node
form.submitFocusNode.requestFocus();
},
),
OnFormSubmissionBuilder(
listenTo: form,
onSubmitting: () => CircularProgressIndicator(),
child : ElevatedButton(
focusNode: form.submitFocusNode,
onPressed: (){
form.submit();
},
child: Text('Submit'),
),
),
],
),
),
Working with scrollable view #
- To work with scrolling list:
final scroll = RM.injectScrolling(
initialScrollOffset: 0.0,
keepScrollOffset: true,
endScrollDelay: 300,
onScrolling: (scroll){
if (scroll.hasReachedMinExtent) {
print('Scrolling vertical list is in its top position');
}
if (scroll.hasReachedMaxExtent) {
print('Scrolling vertical list is in its bottom position');
}
if (scroll.hasStartedScrolling) {
// Called only one time.
print('User has just start scrolling');
}
}
);
In the UI:
ListView(
controller: scroll.controller, // Ready to go 🏃♀️ 🏃
children: <Widget>[],
);
Working with page and tab views #
Test and injected state mocking #
All Injected state can be mocked for test. To mock it in test:
model.injectMock(()=> MyMockModel());
model.injectFutureMock(()=> MyMockModel());
products.injectCRUDMock(()=> MockRepository())
user.injectAuthMock(()=> MockAuthRepository())
And many more features.
Examples: #
Basics: #
Since you are new to states_rebuilder
, this is the right place for you to explore. The order below is tailor-made for you 😃:
-
Hello world app: Hello world app. It gives you the most important feature simply by say hello world. You will understand the concept of global function injection and how to make a pure dart class reactive. You will see how an injected state can depends on other injected state to be refreshed when the other injected state emits notification.
-
The simplest counter app: Default flutter counter app refactored using
states_rebuilder
. -
Login form validation: Simple form login validation. The basic
Injected
concepts are put into practice to make form validation one of the easiest tasks in the world. The concept of exposed model is explained here. -
CountDown timer. This is a timer that ticks from 60 and down to 0. It can be paused, resumed or restarted.
-
Theming and internationalization. This is a demonstration how to handle theme switching and app internationalization using
RM.injectedTheme
andRM.injectedI18N
. -
CRUD query. This is an example of a backend service fetching data app. The app performs CRUD operation using
RM.injectCRUD
. -
Infinite scroll listView. This is another example of CRUD operation using
RM.injectCRUD
. More items will be fetched when the list reaches its bottom.
Advanced: #
Here, you will take your programming skills up a notch, deep dive in Architecture 🧐:
- User posts and comments: The app communicates with the JSONPlaceholder API, gets a User profile from the login using the ID entered. Fetches and shows the Posts on the home view and shows post details with an additional fetch to show the comments.
Firebase Series: #
- Firebase login The app uses firebase for sign in. The user can sign in anonymously, with google account, with apple account or with email and password.
Firestore Series in Todo App: #
TODOS MVC app The same examples as above adding the possibility for a user to sin up and log in. A user will only see their own todos. The log in will be made with a token which, once expired, the user will be automatically disconnected.
--> -->Note that all of the above examples are tested. With `states_rebuilder`, testing your business logic is the simplest part of your coding time as it is made up of simple dart classes. On the other hand, testing widgets is no less easy, because with `states_rebuilder` you can isolate the widget under test and mock its dependencies.**