It's okay to use launched effects to navigate when...

# compose

[Lisandro Di Meo]

It's okay to use launched effects to navigate when a state changes? For example, a login view:

val isLoginError by loginViewModel.loginError.observeAsState()
    val context = LocalContext.current
    LaunchedEffect(isLoginError){
        when (isLoginError) {
            true -> {
                Toast.makeText(context, "Error", Toast.LENGTH_SHORT).show()
            }
            false -> navHostController.navigate(Paths.HOME_PATH)
            null -> { // blah }
        }
    }
    LoginScreen(loginViewModel)

[Joseph Hawkes-Cates]

That seems Ok. I’ve handled this sort of thing in my app by injecting a shared Navigation flow into my VMs. I can then emit Navigation directions to that flow directly from the VM which is collected at a global level and then the global collector calls navHostController as appropriate.

[Lisandro Di Meo]

Can you share your solution? that looks like an interesting approach

[Joseph Hawkes-Cates]

To be fair, I didn’t come up with it. I think I found the idea in this article: https://proandroiddev.com/jetpack-compose-navigation-architecture-with-viewmodels-1de467f19e1c

[Joseph Hawkes-Cates]

He shows a good example and explains why about halfway down the article.

[Joseph Hawkes-Cates]

So we can thank @Syex for this one. 🙏

[Joseph Hawkes-Cates]

it’s worked out great for testability and very easy to use within our application.

[Syex]

You're welcome 🙂

[Lisandro Di Meo]

Thanks! I'll look into that 😄