Bloc: listen to state out of build

[DJafari]

i have a question

i want listen to state, and doing something with new state
for example i want listen to AuthenticationState, when is AuthenticationAuthenticated i want after 3 seconds push to new page, how can achieve to this ?

thanks

[felangel]

Hello! 👋

You can do bloc.state.listen to react to state changes outside of build.

Does that help answer your question?

[DJafari]

@felangel oh thanks,
just another question
i use dio to http requests, is possible use interceptor to catch 403 errors, if occurred, dispatch LoggedOut event to app that push my route to login route automatically ?

(sorry for my bad english, I hope you understand my conversation(

[felangel]

Yeah you can definitely do that! You’ll just need to inject the bloc into your http interceptor and dispatch the event (like you said). If you have a code snippet that isn’t working I’d be happy to take a look but you have the right idea 👍

[DJafari]

i think because i don't have context in interceptor, i can't inject AuthenticationBloc

[felangel]

You can directly inject the bloc via the constructor. You’re right that you can’t use BlocProvider without a BuildContext.

[DJafari]

@felangel
thanks for consultation
thanks for your great library

and i have another question about this idea out of this library
is possible push login route and stop user to back page ?
i know i can hide back icon from appbar, but android users can using back key of phone

[DJafari]

i found that

WillPopScope(
   onWillPop: () {
     SystemNavigator.pop();
   },
   child: ...
);

thanks

[DJafari]

@felangel i faced with a problem

where does i must listen to authentication state ?
i have something :

authenticationBloc.state.listen((state) {
    if(state is AuthenticationUnauthenticated) {
      Navigator.pushNamedAndRemoveUntil(context, '/login', ((Route<dynamic> route) => false));
    }
});

but when state is AuthenticationUnauthenticated, i give this error :

The context used to push or pop routes from the Navigator must be that of a widget that is a descendant of a Navigator widget.

i tested it inside BlocProvider but any success

[felangel]

You need to do that within your MaterialApp widget. I would try moving that logic to the onInit override in your primary app component under MaterialApp. If you're able to share a link to your repo, I can also take a look and try to help.

[DJafari]

sorry my application not exist in git

but i use this pattern for making my app

[felangel]

Out of curiosity have you looked at the Login Flow example here?

[DJafari]

yeah, but my design is different
in my splash page, i have 2 button
login with email
login with phone number

if token set, buttons hides, and waiting for fetch user from api, when fetch successful i pushed route to /home

[felangel]

that's very similar except in your example you are pushing a new route as opposed to in the example I sent we use BlocBuilder and rebuild based on the AuthenticationState. Is there a reason you don't take a similar approach instead of pushing a route?

[DJafari]

on of biggest problem is animating 😁
for example changing home page with login page is not smooth

[felangel]

Ah okay. Have you checked this out? https://github.com/felangel/bloc/issues/18

[DJafari]

@felangel i will look into
big thanks