flutter_vm 0.0.1

A Flutter implementation of ViewModel.

ViewModel Library

A Flutter ViewModel implementation. Use Mixin for use in Statefull Widget or sample contructor for use in Stateless.

In your CustomViewModel you can use UseCase or custom Future.

In your Widget you can listen your stream or use SnapshotBuilder in your build method.

You can see a full example at this repo. Flutter ViewModel Example

ViewModel

class AuthViewModel extends BaseViewModel {
   
  final LogoutUseCase _logoutUseCase = LoginUseCase();
     
   

	//you can listen this in your UI 
  final isUserLogged = BroadcastStream<bool>();

  void login() {
    executeUseCase(_loginUseCase, LoginParams("username", "password"),
        broadcastStream: isUserLogged);
  }

 
}

UseCase

class LoginUseCase  extends UseCase<LoginParams, bool>{
  final UserRepository _userRepository;

  LoginUseCase(this._userRepository);


  @override
  Future<bool> execute(LoginParams params)async  {
    await  _userRepository.login();
    return   _userRepository.getIfUserIsLogged();
  }

}

class LoginParams {
  final String _username;
  final String _password;

  LoginParams(this._username, this._password);
}

Init in StateFull Widget

class _LoginMixinWidgetState extends State<LoginMixinWidget>
    with ViewModel<LoginMixinWidget, AuthViewModel> { //use mixin


  @override
  AuthViewModel getViewModel() => AuthViewModel(); // need constructor

  @override
  void initState() {
    super.initState();
    // now you can access to ViewModel with vm
    vm.getIfUserIsLogged();  
  }
  

Init in StateLess Widget

 class _LoginWidgetState extends State<LoginWidget> {
  AuthViewModel _authViewModel = AuthViewModel(); //basic init

  @override
  void initState() {
    _authViewModel.getIfUserIsLogged();

    super.initState();
  }

  @override
  void dispose() {
    _authViewModel.dispose();// you need to dispose
    super.dispose();
  }

Use SnapshotBuilder

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Center(
        child: SnapshotBuilder<bool>(//need to specify data type
          initialData: false,
          broadcast: _authViewModel.isUserLogged, //broadcast in viu model you listen
          onLoading: Container(), 
          onError: (e) {
          //here you have error
            return Container();
          },
          onData: (value) {
          //here you have data
            return Container();
          },
        ),
      ),
    );
  }
  

Listen Strem

  int _counter = 0;
  
  @override
  void initState() {
    vm.number.stream?.listen((value) {
      setState(() {
        _counter = value;
      });
    });

    super.initState();
  }