I’m building my app in Jetpack Compose and use one...

# compose

[Aaron Waller]

I’m building my app in Jetpack Compose and use one ViewModel for every feature/screen. Now I need to access the login state from everywhere inside the app, I also have a coin system where I need access to from every screen.
How do I accomplish this? My first idea was to put the login state and coin state inside a “MainViewModel” and then use this in every Screen for example in my “SettingsScreen” composable use “SettingsViewModel” and “MainViewModel”. But I’m not sure if this is a good practice to use two viewModels in one screen.
How can I have access to the Login state and the Coins in every screen?

[Rafael Costa]

You can have login state on a repository class that multiple view models listen to 🙂

[Colton Idle]

Yeah. Was basically going to say that you need your login state to live in your App scope and so basically you can create a singleton via Dagger if you use that, or just have this login state in your App class.

[Aaron Waller]

@Colton Idle Thank you.
How should the user class look like? I never injected anything with hilt except of Room, Retrofit and Repositories 😬
Do I use a Data class for that? Or maybe a sealed class?

This is what data I need to access from the user at all places in the app:

data class UserState(
    val username: String = "",
    val isLoggedIn: Boolean = false,
    val isPremiumUser: Boolean = false,
    val coins: Int = 0
)

[Colton Idle]

It can really look however you want it to look like (eg whatever fields you need), but yeah. It took me a long time to realize that for my entire Application, it's fine to have a "CurrentUser" that is available from everywhere.

[Aaron Waller]

@Colton Idle How do I observe this UserState object to see every change everywhere in the app?
If you could check out my StackOverflow question I would be really happy, no one answered yet:

https://stackoverflow.com/questions/72213441/access-the-login-state-from-every-screen-jetpack-compose-mvvm-hilt

[Rafael Costa]

You can use a StateFlow in the Repository

[Rafael Costa]

then all interested parties can collect on it

[Rafael Costa]

(remember to expose it as an immutable StateFlow)

[Rafael Costa]

btw in my personal opinion (but this also depends on your specific case), it doesn’t really make sense to have a “isLoggedIn” boolean. If the user is not logged in, don’t you want to clear all that state?

[Rafael Costa]

if so, I would just use a StateFlow<UserState?> (notice the “?”)

[Rafael Costa]

if user is loggedIn it won’t be null

[Rafael Costa]

if he’s logged out, its null

[Aaron Waller]

@Rafael Costa Thank you so much! Just implemented it like you said and its working perfectly.