Flutter: bloc, how to show an alert dialog

Question

I´m new in the bloc pattern and stream stuff. I want to show up an alert dialog when I press a button, but I can´t find a way to do it. Actually my code is:

Widg         


        

Answer 1

You can use BlocListener for showing Dialogs, Snackbars or for navigating to a new page.

With this approach you may want to refactor to rely on the bloc state rather than accessing the stream directly.

return Scaffold(
  appBar: AppBar(
    title: Text("Title"),
  ),
  body: BlocProvider(
    create: () => YourBloc(),
    child: Stack([
      SnackbarManager(),
      YourScreen(),
    ]),
  ),
);
...

/// This is basically an empty UI widget that only
/// manages the snackbar
class SnackbarManager extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return BlocListener(
      listener: (context, state) {
        if (state.hasMyData) {
          Scaffold.of(context).showSnackBar(SnackBar(
            content:
                Text("I got data"),
          ));
        }
      },
      child: Container(),
    );
  }
}