atom_notifier 1.1.1

An easy to use value notifier wrapper with some sugar syntax

Atom

An easy to use Flutter's Value Notifier wrapper with some sugar syntax. It provides a more friendly and semantic syntax for your project's state management.

Getting started

Add atom as a dependency:

    atom_notifier: 1.0.0

Or running following command on terminal:

    flutter pub add atom_notifier

Then you can import it

    import 'package:atom_notifier/atom_notifier.dart';

Atoms

An atom is a Value Notifier wrapper, which it means it holds a single value for each atom object, native or not.

final atom = AtomNotifier<int>(1);

Unlikely value notifiers atoms have different methods, but the same effect as expected, see in the examples below:

Setting a value

// With ValueNotifier
final notifier = ValueNotifier(0);
notifier.value = 1;

// With Atom
final atom = AtomNotifier<int>(1);
atom.set(2);

Setting Listeners

By default, listen() already get the atom value as an argument, so there's no need to get it with atom.value everytime you want to listen to changes

// With ValueNotifier
final notifier = ValueNotifier(0);
notifier.addListener((){
    final value = notifier.value;
    doSomething();
});

// With Atom
final atom = AtomNotifier<int>(1);
atom.listen((value){
    doSomething();
});

Listening to specific state

// With ValueNotifier
final notifier = ValueNotifier(0);
notifier.addListener((){
    final value = notifier.value;
    if(value is MyType){
        doSomething();
    }
});

// With Atom
final atom = AtomNotifier<int>(1);
atom.on<MyType>((value){
    doSomething();
});

Observers

Observer is a widget which rebuilds everytime your atom value changes.

Observing a single atom

The most basic way to observe your state within a widget would be using AtomObserver.

    AtomObserver<int>(
        atom: counterAtom,
        builder: (context, state) {
          return Text(state.toString());
        },
    ); 

But, there will be cases where you have more complexes states, a async request status can be a good example, so, with value notifier you usually would need to check your state type and return a widget according to it, but with atom you can use PolymorphicAtomObserver

    abstract class FutureStatus{}
    class InitialState implements FutureStatus{}
    class LoadingState implements FutureStatus{}
    class SuccessState implements FutureStatus{}
    class ErrorState implements FutureStatus{}

    PolymorphicAtomObserver<FutureStatus>(
        atom: myAtom,
        defaultBuilder: (value) => const Text("Initial or Error"),
        types: [
          TypedAtomHandler<LoadingState>(
            builder: (context, value) => const CircularProgressIndicator(),
          ),
          TypedAtomHandler<SuccessState>(
            builder: (context, value) => const Text("Success, dude!"),
          ),
        ],
    );

Observing multiple atoms at once

You can use MultiAtomObserver to handle more than one atom at once in the same widget, this way, everyime an atom inside atoms prop has it value changed it rebulds

    MultiAtomObserver(
        atoms: [index, character],
        builder: (context) {
          final name = character.value;
          final id = index.value;
          return Text("$id: $name");
        },
    ),

Application States

Usually your controllers will have some kind of behaviour just like the example I showed on PolymorphicAtomObserver, where you want your UI to reflect the usecase/service/whatever status. You can use AtomAppState which by default has an extension that makes it easier to add listeners to it.

    final atom = AtomNotifier<AtomAppState<String, int>>(InitialState());
    atom.onState(
      onError: (e) => counter++,
      onSuccess: (e) => counter--,
      onLoading: () => counter = counter * 2,
    );