Flutter bloc - Show snackbar on state change

Question

I am trying to log in with Google. When googleSignInAccount I yield new state with PlatformExecption. Now, How can I access that value in order to do some changes.

try{
    final GoogleSignInAccount googleSignInAccount = await googleSignIn.signIn();

    if(googleSignInAccount == null){
     yield GoogleLoginErrorState(error: PlatformException(code: 'user-cancel'));
    }
}

my state.dart

class GoogleLoginErrorState extends GoogleLoginState {
  final PlatformException error;
  GoogleLoginErrorState({this.error});

  @override
  List<Object> get props => [error];
}

my BlocBuilder

if (state == GoogleLoginErrorState()) {

        }

score 2 · Answer 1 · answered Aug 24 '21 at 20:13

For side effects such as showing snackbars / dialogs or navigating to another screen, you have to use BlocListener, something like this:

  BlocListener<YourGoogleSigninBloc, YourGoogleSigninState>(
    listener: (context, state) {
      if(state is GoogleLoginErrorState){
        // show snackbar here
      }
    },
    child: YourWidget(),
  )

you can also use BlocConsumer instead of nesting BlocListeners and BlocBuilders like this:

BlocConsumer<YourGoogleSigninBloc, YourGoogleSigninState>(
  listener: (context, state) {
    if(state is GoogleLoginErrorState){
        // show snackbar here
    }
  },
  builder: (context, state) {
    return YourWidget();
  },
)

score 1 · Accepted Answer · answered Aug 24 '21 at 18:47

1

In the bloc builder,

if (state is GoogleLoginErrorState) {

}

This checks if the state data type is GoogleLoginErrorState

And use the state

Text(state.error.code)

answered Aug 24 '21 at 18:47

NirmalCode

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Flutter bloc - Show snackbar on state change

2 Answers2